fat-600: You might need to update your bios. I accidenetly put my PC in to sleep twice (vista, so S3 sleep IIRC) and it locked my PC up. I then did it on purpose to test it and it locked up again. Updated my bios to the latest one and it works every time now - there was a description on the bios saying that it fixed a certain CPU (3GHz model, mine is 2.66GHz) in S3 sleep mode so I thought I would gve it a try and it worked.