As the topic says, my game crashes randomly, but seemingly only under specific conditions that I can't figure out. I also have searched several times for people with similar issues but haven't found any.

From what I remember, I have crashed when:

- Twice browsing the High Hedge shop
- Trying to loot the tree at the nashkel mines that has the Wand of Cold in a unmodded game (it had armor instead this game)
- Trying to loot a kobold in the mines
- While identifying items at the Nashkel store
- While switching between inventory screens after resurrecting a party member at the Nashkel temple

It seems to be related to looting and shop windows, but I have no idea how to fix it. I'm running Baldur's Gate Trilogy with the following mods (not all components - for example I have none of the 'Tougher' stuff, only AI improvements)

BG2 Fixpack
BG1 Unifinished Business
BG2 Unfinished Business
BG1 NPC Project
Spell Revisions
Item Revisions
SCS and SCS II
BG2 Tweaks
Widescreen Mod
Level 1 NPCs
Item Randomiser
1 Pixel Productions

The only thing I can think of is 1PP as this is the first time I'm using it, but I'm not sure. Any ideas?

The widescreen mod needs to be installed last, or these kind of things can happen. You also MUST have a completely clean (no fixes, mods, tweaks of any kind) BG1 folder when you install BGT.

Would a full reinstall of BG + all mods be necessary? Is it possible to preserve my saved game?

If you did not have a squeaky clean BG1 folder when you installed BGT, then you MUST uninstall and re-install everything. As I said, it is imperative that BG1 folder is completely virgin when you install BGT, because it uses BG1's resources, and must be clean. When you reinstall, follow a sensible install order. That install order link is specifically for TuTu, but it is quite relevant to BGT also.

The widescreen mod makes preserving your saved games an issue if you do not install it at precisely the same resolution as was used in your saved games, because it modifies assets that are stored in your save games. By the way, you don't actually need the widescreen mod if you are using BGT, because the BG2 engine supports sensible resolutions that won't affect your save games -- use BGConfig.exe and enable the unsupported resolutions.

Not quite, there are several mods which are recommended to be installed after the widescreen mod. You need to perform a full reinstall.
Your saves are gone, you need to restart.

I very very very strongly recommend you do not use BGT.

1. the more mods the more bugs. And BGT necessitates more mods because of all the BG1 and BG2 specific mods.
2 BGT is pointless, BG2 still assumes you finished BG1 with the standard party, it still returns to live any NPC you got chunked, etc. All that changes is that NPCs keep their XP from the end of BG1 (which takes 1 console command per each of them to set manually)
3. BGT and BGTuTu are VERY specific about mod install order... BG2 by itself isn't really.

I managed to complete my BG1 portion of my BGT install (limping to the finish line with only slightly broken game) and then recreated my character for BG2.

I would also prune away mods I don't absolutely NEED. And consider BGEE

PS. I am not saying BGT is individually responsible for the issue. But that you could shorten your mod list significant;y if you weren't using it.

Also, just a reminder. A mod can only be reinstalled/updated/modified if it is the LAST mod you installed. If you installed ANY other mod afterwards then making any changes to previous mods will corrupt the game and saves. Save compatibility also depends on mods being installed in an exact same order using exact same components in exact same selection of features. So once you start a game, you do NOT touch any mods anymore until you are willing to lose those saves (aka, finished the game and is done with them)

Of those listed by the OP, the widescreen mod needs to be installed last. I wasn't referring to every mod on the planet. This is just not true. Other than mega mods, I am continually altering mods, and mod orders, and/or re-installing them, including my own, without ever having lost a game because of it. When the mod is a mega mod, that is quite different. So long as one mod does not cause specific conflicts with another, they can be happily reinstalled (with weidu) at any time.

1. from your phrasing I thought you were
2. IIRC several of those mods OP listed are best installed after widescreen mod. Just because the save game successfully loads without the game crashing doesn't mean your game isn't corrupted. The most common corruption when doing what you describe is tlk table corruption, meaning some dialogs will be randomly mixed up. There is a good chance you wouldn't even notice it... or it can lead to serious issues.

If the tlk table is messed up, believe me you are going to notice it. Your statement is still misleading.