Vegas Pro 11(release 701)/Vegas 12 Playback Problems & More

I have been running Vegas 11 Pro build 683 on 2 machines. One running windows 7 64 bit, the other windows Vista 64 bit. The machines have NVidia Cards (550 Ti & 570 HD). Both are 3.2 i7 processors (an 8 core machine & 12 core machine) with 6Gb & 16Gb RAM respectively. Version 11 build 683 runs quite well. The upgrade to Version 11 build 701 & subsequesntly to Version 12 causes major crashing. I can't even playback video on the timeline without a crash. Both machines stutter during playback with or w/o GPU acceleration activated. I also noticed that V11 build 683 uses about 20% CPU resources when playing video (displayed in the resource monitor. V12 uses over 70% GPU resources when playing video on the timeline??? All my video drivers are up to date. I can't even run V12 at this time ... all my work has to be done in V11 build 683.

Should it matter? I have often run 2 versions and never experienced a problem. Also, pre release V12, the release of V11 build 701 caused the same problems ... I had to roll back to V11 build 683

[Steve Rhoden] "I would not have mentioned it if it didnt matter. Vegas 11
was not too wholesome, it had issues thru all its builds,
Vegas 12 however is stable in its first release and in
certain circumstances, i discovered that having them both
on a system affects Vegas 12 stability.
There is never really a need running two versions of Vegas
if you have the most current release."

Two points, or questions:

-- John Rofrano has often said in the forums, that he has up to 3 older versions of Vegas installed on the same machine, that this is one of Vegas' strengths.

-- I've had to keep past versions of Vegas installed due to the latest version having problems opening up older nested VEG files.

Indie Filmmaker

Thank You ... it's really weird. I uninstalled vegas 11 & 12, tried installing only vegas 12 and still, when opening a V11 project, it stuttered & then crashed on video playback. BUT when I rebuildt the project in vegas 12 only by pulling the original media back into the project, it seemed to run much better!

Thank You