VS displays 'Out Of Memory' when I try to play back file!

[mindzcape]

Hi all!

How frustrating! I'm running VS10 and have 5 seconds of footage to complete my 10 minute project (16 hours editing). Just as I go for a play review, I have a message pop up "Out of Memory". I now can't preview the project let alone edit accurately. I tried converting my project to a simple low resolution video file for play back to find most files were missing or moved 'out of time'. I've been using VS for a long time now and have never had this.

I can't find any documentation on this error. Have I simply placed too many files, effects and transitions in my project and/or for my PC size?
Running 1GB RAM. I also note that I may need to upgrade my Video Card etc etc. I noticed in VS9 that I filled The file manager and it wouldn't let me add anymore files. Could having an extremely full library (library manager) effect anything?

Any ideas would be greatly appreciated as I feel the problem could be caused by a number of reasons...