There's two things you can try;

1) A file recovery utility;

http://www.pcinspector.de/Sites/file...htm?language=1

(I've used the above with success. Just save the recovered files to a different partition.)



2) A System Restore.

If it were me, I'd use the first option before a system restore.



"Is the D: drive a seperate physical hard disk, or is it another (second) partition on your first (only?) hard disk?"

You didn't answer this. If it's a seperate hard disk, disconnect the power and data cables until the recovery software is loaded and you're ready to start. Use D: as little as possible before you attempt a file recovery.

Once you get your files, run a thorough check on D:. It may be failing. If you know the make of the disk;

Hard Disk Analysis Tools - Major manufacturers