Corrupted files are usually a hardware issue, so while I wouldn't rule LR and PS out entirely, I'd be looking for hardware issues first. Card reader, memory, hard drive. And are you always importing to the same hard drive?
And I'd try a clean catalog and clearing the ACR cache too.
I appreciate you taking the time to reply. I did use 2 differnt hard drives and 2 different CF cards. The only hardware I changed at about the same time it started was I got a DeLock Firewire CF card reader. Althoguh I did try my old USB card reader and still saw the same problem. Will clear the ACR cache - just need to work out how to do it
Have you tried running something like Memtest too?
There's a purge button for the ACR cache in the LR Preferences dialog.