"Here are some things to try.
1. Verify that your TEMPORARY FILES folder for Vegas has enough space. See PREFERENCES.
Shutdown Vegas. Then go delete everything in the Vegas TEMPORARY FILES folder before restarting Vegas.
If for some reason, you can't delete all of Vegas' temporary files, then see #2.
2. Is Vegas crashing on you? Some times when an app crashes, the process doesn't completely die and get cleaned up by Windows. So some of the files it creates and uses, including temporary files, cannot be released back to Windows. So even if you restart Vegas, the new Vegas process may not be able to read and write to some of the files it needs.
3. Maybe one of the effects plugins or codecs you are using is having problems with Vegas. Perhaps you are using plugins and codecs that are incompatible with your 64-bit Vegas. Update all plugins and codecs Vegas maybe depending on. Ensure they are 64-bit compatible."
Source:
http/forums.creativecow.net/thread/24/945501
"Clean the Vegas Pro or Movie Studio Platinum Program Cache
Sometimes mysterious alien artifacts can build up inside the hidden program cache and caused bizarre behavior. Do the following to clean out the Cache and Reset the program. Please note that this will reset the desktop display for the program.
Hold down the CTRL and SHIFT keys on your keyboard, and at the same time double click the program icon on your desktop to boot the program.
Select Delete Cache and Yes
The cache is now cleaned."
Source:
https/www.moviestudiozen.com/doctor-zen-faq/157-vegas-crashes-when-importing-1080p-video