Bravster: Finally manged to get this little gem working and completed it in a very long session that has left me addicted and sleep deprived! Good work Gog!
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Uninstalled and Deleted any traces of WC4 from the Registry
Disable All Firewall and AV Protection
Downloaded a Fresh WC4 From Gog
Installed WC4 with no Protection OR Internet Connection
Disabled Firewall/AV Protection for 10 minutes & Launched the Game in 98 compatibility mode.
This seemed to be the only thing that worked for me as I tried all that was suggested,
Hope this may be helpful to someone in the future, it seems a bit Over the top to have to do every little step but it's working regardless.
A small thing to note may be that the Videos can chop and jump around from time to time.
I have tried all of the suggested fixes and nothing seems to work. I have a Windows 7 system with the latest Nvidia drivers. I have a message into GOG but no reply yet. I would guess there is a lot of bugs yet to be worked out.