Pre-note: I am on a trial account

My problem is I can't go 2-3 mins on a certain project without it crashing with the "not responding" message. If prior to that I use certain tools like the undo button or trim buttons, it will freeze and "0%" will be added to the top left before the title.

I've watched about 5 vids and read 10 various posts on how to solve crashing, and no solution has worked. Additionally, I don't know why it is this project in particular. It is my longest/most complicated project, but only has maybe 10 minutes of footage and audio in it, nothing crazy.

I figured initially it was to do with the program, but old, smaller, projects work fine. Either my file is corrupted, my computer is running out of memory, or something unseen. Sony Vegas 15 comes out in 2 days (hopefully with a trial), and I'm not sure if the file will be able to transfer, and if it would fix anything anyway.