pace studios

Protools Le

Help!!
Please can anyone give me the advice on the following;

I have a Power Mac G4 with OSX software with Pro Tools LE 6.4 and MBox.
The computer has been operating very slow so I cleared the trash.
Carried on working in Pro Tools, went to save the file and it came up as 'save as' even though the file already had a name. I saved it in one of the 3 folders that I save everything. As soon as I saved it it came up as 'pro tools has unexpectedly quit'
I then looked for the files in the folders and ALL Pro Tools files (current and previous) has gone.
Now when go through the harddrive to try and find these files it comes up with 'original folders can not be found'

I looked in the log book and this is what it says
'23.26 local/host/applictions/digidesign/protools/protoolsle6.4:usingFIXEDploicy

Please Help as I am desperate and spent all day recording tracks which I have now lost!