CDRWin problems

[koalabear1]

I have been using a demo copy of CDrWin to backup my PS2 games and it has been working brilliantly. All of a sudden Im getting a error when i load it up. Error is:

"Load Disc" command failed on device 0:0:0
Device contains no disc or is not ready.

Now, I have come across this problem in the past and by doing a defrag, the problem disappeared. This time it hasnt. I have also downloaded the CdrWin Ver4 again but the problem still persists. I am using a Iomega Zip 650 which is what ive backed up all my PS2 games on. Any ideas guys??