I'm using BG1/BG2 Weidu and in BG1 when I try to enter Beregost for the first time, the game crashes to the desktop. I tried running the fix - beregostcrashfixer19 but it didn't help.

There is no such thing as 'BG1/BG2 Weidu'. Weidu is a third party Infinity Engine patcher tool. It sounds to me like you mean BGT Weidu, however I am confused, because the well known Bergost crash bug only affects TuTu installations. So, it would help if you gave precise information about your version and which mods you are using -- a weidu.log would help, too.

This is what I have installed;
Gibberlings BG2 fixpack
BGT WeiDU 1.18
BG1 & BG2 Unfinished business
BG2 TweakPack

Please post the contents of your weidu.log here.

It won't let me post it. Maybe it's too big. I'll try to break it up;

// Log of Currently Installed WeiDU Mods
// The top of the file is the 'oldest' mod
// ~TP2_File~ #language_number #component_number // [Subcomponent Name -> ] Component Name [ : Version]
~DDRAWFIX/DDRAWFIX.TP2~ #0 #0 // DDrawFix -> Force DirectDraw Emulation: v1.0
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #0 // BG2 Fixpack - Core Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #1001 // BG2 Fixpack - Game Text Update -> GTU Classic (from Baldurdash, by Kevin Dorner): v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #3 // BETA Core Fixes (please check the readme!): v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #100 // Party Gets XP for Sending Keldorn to Reconcile With Maria: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #101 // Improved Spell Animations: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #102 // Cromwell's Forging Actually Takes a Day: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #103 // Mixed-Use Dagger Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #104 // Ghreyfain's Holy Symbol Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #106 // Giants Receive Penalties When Attacking Halflings, Dwarves, and Gnomes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #107 // Remove Dual-Classing Restriction from Archers and Stalkers: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #108 // Remove Second Attribute Bonus for Evil Path in Wrath Hell Trial: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #109 // Corrected Summoned Demon Behavior: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #110 // Additional Script Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #111 // Bard Song Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #112 // Wizard Slayers Cause Miscast Magic on Ranged Attacks: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #113 // Additional Alignment Fixes: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #114 // Change Free Action to Protect Against Stun: v10
~BG2FIXPACK/SETUP-BG2FIXPACK.TP2~ #0 #116 // Remove Thieving Start Bonuses from Bard and Ranger Skills: v10
~SETUP-BGT.TP2~ #0 #0 // Baldur's Gate Trilogy - Core: 1.18 (28 Apr 13)
~SETUP-UB.TP2~ #0 #0 // The Kidnapping of Boo by Cliffette: v23
~SETUP-UB.TP2~ #0 #1 // The Suna Seni/Valygar Relationship: v23
~SETUP-UB.TP2~ #0 #2 // Kalah and What He Was Promised: v23
~SETUP-UB.TP2~ #0 #3 // "Cat and Mouse" (Bodhi hunts you in Spellhold) by Ghreyfain: v23
~SETUP-UB.TP2~ #0 #4 // Gorje Hilldark and the Extended Illithium Quest: v23
~SETUP-UB.TP2~ #0 #5 // The Pai'Na/Spider's Bane Quest: v23
~SETUP-UB.TP2~ #0 #6 // Restored Crooked Crane Inn: v23
~SETUP-UB.TP2~ #0 #7 // Restored Encounters: v23
~SETUP-UB.TP2~ #0 #8 // Artemis Entreri in Bodhi's Lair: v23
~SETUP-UB.TP2~ #0 #9 // Corrected "Xzar's Creations": v23
~SETUP-UB.TP2~ #0 #10 // Restored Hell Minions, by SimDing0: v23
~SETUP-UB.TP2~ #0 #12 // Item Restorations: v23
~SETUP-UB.TP2~ #0 #13 // Yoshimo's Original Portrait: v23
~SETUP-UB.TP2~ #0 #14 // Anomen's Original Portrait: v23
~SETUP-UB.TP2~ #0 #15 // NPC Portrait Restorations: v23
~SETUP-UB.TP2~ #0 #16 // Corrected BAMs and Scripts: v23
~SETUP-UB.TP2~ #0 #17 // Corrected Character Names and Biographies: v23
~SETUP-UB.TP2~ #0 #18 // Restored Minor Dialogs: v23
~SETUP-UB.TP2~ #0 #19 // Restored Bhaalspawn Powers, by David Gaider: v23
~SETUP-UB.TP2~ #0 #20 // Extended ToB Item Descriptions: v23
~SETUP-UB.TP2~ #0 #21 // Throne of Bhaal Minor Restorations: v23
~SETUP-UB.TP2~ #0 #22 // Justifier Kit: v23
~SETUP-UB.TP2~ #0 #23 // Feralan Kit: v23
~SETUP-UB.TP2~ #0 #24 // Sarevok's Remorse: v23
~SETUP-UB.TP2~ #0 #25 // The Murder of Acton Balthis, by Kulyok: v23
~SETUP-BGTMUSIC.TP2~ #0 #0 // Baldur's Gate Trilogy - Music -> Full Baldur's Gate and Tales of the Sword Coast Music
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #10 // Remove Helmet Animations: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #20 // Change Imoen's Avatar to Mage: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #30 // Change Nalia's Avatar to Thief: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #40 // Change Viconia's Skin Color to Dark Blue: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #50 // Avatar Morphing Script: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #60 // Weapon Animation Tweaks: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #70 // Icewind Dale Casting Graphics (Andyr): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #80 // Restore SoA Load Screen Logo (ToB Only): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #90 // Disable Portrait Icons Added by Equipped Items: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #100 // Commoners Use Drab Colors: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #110 // Icon Improvements: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #120 // Change Avatar When Wearing Robes or Armor (Galactygon): v14

Here's more;

~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #130 // Force All Dialogue to Pause Game: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #140 // Fix Boo's Squeak: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1010 // More Interjections: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1020 // Alter HP Triggers for NPC Wounded Dialogues: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1030 // Reveal Wilderness Areas Before Chapter Six: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1036 // Make Cloakwood Areas Available Before Completing the Bandit Camp -> All of Cloakwood Except the Mines: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1040 // Improved Athkatlan City Guard: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1050 // Gradual Drow Item Disintegration: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1070 // Improved Multi-Player Kick-out Dialogues: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1080 // Add Bags of Holding: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1090 // Exotic Item Pack: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1120 // Stores Sell Higher Stacks of Items: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1130 // Reputation Resets in BG2 (BGT Only): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1140 // Gems and Potions Require Identification: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1150 // Shapeshifter Rebalancing: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1160 // Multiple Strongholds (Baldurdash) -> No Restrictions (Baldurdash): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1170 // Bonus Merchants (Baldurdash): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1180 // Female Edwina: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1210 // Use BG Walking Speeds (BETA): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #1220 // Allow Cromwell to Upgrade Watcher's Keep Items: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2020 // Two-Handed Bastard Swords: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2030 // Two-Handed Katanas: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2035 // Two-Handed Axes: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2040 // Universal Clubs: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2060 // Weapon Styles for All: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2080 // Delay High Level Abilities: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2090 // Change Experience Point Cap -> Remove Experience Cap: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2100 // Allow Thieving and Stealth in Heavy Armor: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2120 // Allow Arcane Spellcasting in Heavy Armor: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2140 // Expanded Dual-Class Options: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2151 // Wear Multiple Protection Items -> No Restrictions: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2160 // Alter Weapon Proficiency System -> Rebalanced Weapon Proficiencies: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2170 // Cast Spells from Scrolls (and Other Items) at Character Level: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2192 // Limit Ability of Storekeepers to Identify Items -> Hybrid of Both Methods: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2200 // Multi-Class Grandmastery (Weimer): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2210 // True Grandmastery (Baldurdash): v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2240 // Un-Nerfed THAC0 Table: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2250 // Un-Nerfed Sorcerer Spell Progression Table: v14
~BG2_TWEAKS/SETUP-BG2_TWEAKS.TP2~ #0 #2261 // Alter Mage Spell Progression Table -> PnP Table: v14

Use BETA tweaks at your own risk! This tweak above is known to corrupt Garrick's creature file, especially if your main character has passed level 2 (Garrick's lowest creature file is untouched, that is why the level matters). Uninstall this tweak, or delete/restore the original Garrick creature files from/into your override folder.

That worked, thank you!

Excellent.