Extensive technical expertise isn't always neccesary to try and help solve problems
I don't run Vista myself but the first things I'd do to try and solve it are;
Disable the Aero interface,
Disable UAC (Or User Access Control)
Temporary disable your firewall and your antivirus,
to see if this fixes your situation.
May not be necessary, but you can cause more problems then you solve. For example the above three should be elaborated to be the most helpful:
To disable Vista's visual themes for a specific program:1. Right click the programs shortcut, or .exe file and go to 'properties.'
2. Switch to the compatibility tab.
3. Check 'disable visual themes' if you are having graphical issues. On older games, switching on 'Run in 256 colors' and 'Run in 540 x 480 resolution' can help.
4. If getting errors, check 'Run this program in compatibility mode for:' and select a relevant version of windows.
I'll note that I am currently using none of these, and my game runs perfectly. As I recall, on my old GeForce 6800 I needed one or more checked - but on my new 8800 I don't.
Disable UAC:When installing mods, tweaking INI files, or generally playing around with 'protected' directories, such as your BG2 install directory, you should disable UAC. You can do this by going to the control panel, user account settings. Unless you have 110% confidence in your security system's competence, I'd recommend turning this back on after you're done with your tinkering.
Possible Problem with Anti-Virus/FirewallI know that some firewalls (such as COMODO) have problems with BG2. It is best to switch your firewall off, and unplug yourself from the internet to test if this is the case. If this is the problem, most security software have a setting to allow a program more privileges, which should fix any issues you're having.
Anywho, I stand by my suggestion of trying it in windowed mode and getting back to us if that fixes it. If not, someone should think of something.
When your 3dMark scores lower by 20% you'd uninstall Vista and return that crap too . . . ur, toss your downloaded copy in the trash.
That isn't surprising. You forget that 3dm runs Dx9 in emulation. Seeing as 3dm's development cycle is slow enough where they haven't kept up with Microsoft's sluggish Windows development trends... well, you can see the result. 3DMark Vantage should make things much, much better. As it is, 3dm isn't accurate with Vista/Dx10 because it doesn't know how to handle 3.0 Shaders and oodles of other things.