I missed the 64bit Question there. You probably have to install the .net64 files. It is also possible you have to add the amd processor .exe into your .ini file (though I had no issues with that ever and I've got an AMD Athlon FX64 X2 processor.) Off the top of my head, I cannot recall the exact files, however, on your NWN2 Installation disc, there is a folder called Prereqs and in there is a starting file for loading up the .net framework. There is also a file there for loading up the 64 bit version (I think it will let you choose if you just take the basic startup exe and run that.)
[edited addition]
I just realized that you reported that you have your HD separated into two partitions. One for your OS and one for your other stuff. This may be the cause in the toolset issue. Check your .ini files and ensure that the toolset has it's path set to the proper location. I don't think this should cause the issue you're having, but who knows? Sometimes it's the little things between a game's ini and the system's ini files that can cause issues. You should also verify your path for that in the ini files and make sure there are no conflicts there.
I do strongly suspect, though, that this might be an issue with .Net 64bit.
[/edited addition]
Additionally, you should read the toolset FAQ, as it does address the Windows XP/ Vista/ Win7 issues that are the most prevalent. With XP the biggest issues are hardware (which doesn't seem to be the issue here) drivers (also doesn't seem to be the cause) then DirectX 9.0c (loaded) and then .Net. .Net is tricky at times and this is possibly the cause. Like I said, I missed the 64bit portion of your post.
It has been reported at times that simply attempting to install the ,net from the disc has solved some issues for folks. It's like without that particular version level, some of the .net featues the toolset uses don't get 'turned on' during the installation and it's only on some systems. Very strange.
I can't say this will solve it for you, but it's definitely worth a shot. Also you should then attempt to update your .Net framework through the Microsoft Update Site and see how that goes.
Best of luck to you, we always welcome more toolset users,
And best regards/welcome to the madness,
dunniteowl
Modifié par dunniteowl, 07 octobre 2010 - 11:03 .