How much of an impact doesthe GPU have on the Studio15 Ult. program?

Video card (MAYBE) causingissues with Studio15 and other programs. I have been experiencing lots ofissues with my Studio15 Ultimate, and thought it was the program. Every time Iwould be in the EDIT MOVIE mode, I would add a simple transition, and thescreen would turn white ("GHOSTING"), and then I would get the("NON-RESPONDING") message all the time. So I uninstalled PinnacleS15, until I know what's causing these issues. These happen online and offline.
Then I thought it maybe theWin7, then the CPU, and then I was talking with MSI, the maker of my P-35MS-7345 Platinum Motherboard, Socket 775, and they told me it was most likely the GPU. he hears the same thing with the MSI GPU's.
self-build is about 4 anda half years old, same as the GPU, and when I originally bought it, I was usinga 32 Bit Win XP, but now I use WIN7 (64) and have updates on my GPU all thetime.

Windows7 PRO 64 (SP1)

700w Thermaltake PSU
Nvidia GeForce 8600GT Pci-e GPU
American Megatrends Inc. v.1.10 / 11/10/08 /Current Bios version - 1.A0 / Online v. 1.C0 / VGA Bios v. /Installed Physical memory -8GB DDR2 / Available Physical memory -6.12GB /DirectX 11
performed a VIDEO CARD STABILITY TEST v. I ran this utility and the benchmark for my Graphic card, after 9hours of testing came back a 95.

Has anyone else experienced these issues with their GPU,while working in S15, and what was your problem? Thanks!