Sorry it took me so long to respond…
Essentially, the problem with my project was I had so many different files in my project media, Vegas was overwhelmed when it tried to either open the project file or render.
Here’s what I did:
With Vegas running, pull up the task manager and check ‘processes’ (windows), you’ll see something called ‘FileIOSurrogate’ or similar. Basically, this process is how Vegas “points” to the actual files used in the project media window. When I was having problems, ‘FileIOSurrogate’ was running around 800,000 – 900,000K. To get things running smooth again, I had to drop it down around 200,000 – 300,000.
My project was about 24 minutes long and had over 200 different files in project media including 4 different video file types, narration audio clips, music clips, sound fx, etc.
Once it got to the point where Vegas would freeze trying to open the project file, I had to move the location of the source files so Vegas wouldn’t “see” them when it opened. When the dialogue window came up during opening process, I chose to ignore all missing files and open the project. Then I told Vegas where to look for just the narration audio files and I rendered those to a single mp3. I removed all the individual narration audio files and replaced them with the single narration mp3 I rendered which reduced the size of the FileIOSurrogate process.
I repeated this process and rendered my soundtrack into a single file and as many sections of my video as I could into single files and then removed the individual files from project media until the FileIOSurrogate process reduced and Vegas stopped locking up…and I could render the entire project without a problem.
Someone with a better technical understanding of Vegas may be able to explain what was actually causing my problem, but that’s my low-tech explanation.
Hope that helps, I know I was very frustrated with this issue for about 2 weeks.