I just experienced this same problem tonight. I don't have any subfolders, just the two: Complete and Incomplete. What is strange (and maybe this will help you out GK) is that the computer started getting sluggish right after that error occurred. Had no idea why. I checked the running processes and it showed the folders taking up 99% of my CPU! I manually shut them down (the X didn't work) and the CPU went to normal. When I reopened the folder all of the files were there.