Ive just lost 3 files because of some problem when saving them... Everything was working, or is working fine, Ive finished the pieces, saved them, and wen I had to work on them again... problem on opening... the file "was gone"?... Any idea of what is happening?

Are you useing Tech Tool Pro on the Mac? If so, it's a problem with TTP mistaking the the original file as the Temp file. The solution is to make an "Exception" in the TTP preferences for the Carrara files.

Forgot to mention that the files will still exist in Trash Cache and can be recovered with no lost data using the Trash Cache feature or using something like Norton Utilities looking for invisible files. However, if you've done much computing work in the mean time, the files may have been overwritten. :(

(PC) the problem is that the file exists, but doesnt open, they are in the same folder Ive recorded them and, when I try to open the file... error

I'm no expert, but it sounds like your SWAP FILE problem. A year ago, I experienced a simular problem. My problem was my sawp file was set to my 1Gig hard drive and the project's temp file was using all the HD space. When it came time to save the project, it had nowhere to save to. Check under PREFERENCE and see where your Swap file is set to. Also check to see how big the project file is. Personaly, I still use a PhotoShop golden rule; "A project size open is 3x it's close size. Solution is set your swap file the another HD and buy more RAM.

I'm working on a 850MHz Pentium with 256MB RAM with more than 8GB free on my hard drive. When I finish the job, it will let me save... but wont open again, poping up that message that you see above. Is it possible to be a swap file problem? or a problem on the software (need to install again)? or maybe I must change the save to another folder? problem with the the objects in the file? I'm totally lost...