I have this very unique situation at hand.. I'm leaving out some details due to the complexity of it all. So I bought a new Dell (9gb ddr3 ram, core-I7 750gb WD internal....) that is more than suited for editing. It came with vista 64bit SP2 already installed on it. I then installed Vegas Pro 8 and edited off my internal 750gb drive without ANY problems for like 5 months.... Recently I installed windows 7 and immediately (within 5 min after installing) noticed that when I played video on my timeline, that the video preview window would hang/freeze then cause vegas to completely lock-up. I tried reinstalling it like 15 times, and even tried the trial version (vegas 9) from sony... Still, same problem. I assumed it was a driver issue so I downloaded all the latest drivers, but it still froze after a few min of editing. I desperately needed to edit so I reverted back to Vista sp2 64bit (which worked well before and works great on my laptop) and to my surprise it did the same thing... I even installed the drivers that came with the computer on a disk-and had Dell remotely access my computer to make sure the drivers were correct.. At this point I considered that it could be a failing HDD, but thought that the coincidence of this all happening was JUST after installing a new OS it would have to be a driver. But I ended up buying a new 1tb 7200 WD SATA... Same crap. Does anyone have any ideas what this could be? I'm 100% certain it's not vegas since I've never had it lock-up on me before. It's something to do with my computer reading from my interal. This is the twist... It edits FINE with an external USB hooked up to it. I don't understand! I went into my power mgnt settings and made sure that my HDD doesn't sleep. No viruses on my machine either....

Did you do an upgrade to Win7 or a clean install?

Ya, it sure sounds like you made the mistake of trying to upgrade Vista to Win7. Wipe that drive and install Win7 clean. Or buy another drive and do it if you want to keep the data on that drive intact.

Thanks for your responses... It's nothing to do with the OS. I tried reinstalling Windows 7- 3 times, (one with 64bit, one 32, then back to windows vista 64, then back to windows 7 64bit) It's not the OS. Clean install. I can play back my native MXF files from the hard drive without any hang ups. I also tested my memory with the windows diagnostic test and that came back clean. This is a very unique problem. My uncle is a computer programmer and my father a network admin and they can't figure it out. My BIOS is up to date..... In fact, everything is up to date with drivers and such (tried rolling them back too). I considered that if could be my graphics card failing, but with the sheer conincidence of this problem occuring immediately after the OS change, I pretty much ruled that one out. And also that I can, and have had to edit with my external, made me think it's not a card issue.

Ah. Well, if you've already tried a clean install and it still locks up, it's some sort of hardware issue. I assume it's under warranty? Rather than spend countless hours trying to track it down, I'd return it for replacement. Really, after all this hassle it's liable to be the motherboard anyway. Why agonize over the coincidence that it failed around the time you installed Win7.

But it would be nice if you could get some other app to freeze. Does Windows Movie Maker play from the timeline?

Just a shot in the dark here, but does it always hang at the same spot? IOW, any chance it's a file that Vegas is having trouble handling... I seem to run into that random glitch all the time, with one file or function (titles). Particularly in rendering, it's a PITA.

One other thing you might try is downloading Vegas 8.1 - it seems to be more stable on my Win7/64 machines so far, and 8.0c is more problematic, seeming to have more rendering lockups than before... Looking like I'll have to edit in 8c, and then render in 8.1 (faster anyway!).

I'm not sure all the intricacies of the problem either, as I'm really just in the stage of upgrading things and finding glitches/workarounds for things that go "bump" in the machine.

Things like the Contour ShuttlePro locking out the screen saver/sleep functions in Win7... apparently I'll just unplug it when not in use...