They were Messenger plus logs and they were encrypted i think but
it wont let me copy them at all back onto the pc, it comes up with cannot read the source file.
when i click on them to open them straight from the disc it comes up in the messenger plus chat log viewer but says 'page cannot be displayed'
Are you sure that your disk isn't scratched, damaged in any way and was written to successfully? I've had problems like this due to scratches... also, it could maybe be some sought of permission problem.
The Disc Definately works, because, before i re-loaded windows, i tried the disc out and it worked, and so did the chat logs. but after it was reloaded, they wouldnt work anymore, but everything else on the disc still works.