Somehow the folder gets corrupted. When you delete it it is rebuilt and then it works.
You might want to run a
chkdsk. Notice in the tutorial there is a check box for "scan for and attempt recovery of bad sectors", go ahead and check that box as well. Once you set it up it will run the next time you reboot. You might want to set it up and reboot just before going to sleep because it may run several hours depending on the size of your hard drive. This will check to see if the hard drive has bad sectors; a few bad sectors is normal but many bad sectors is usually a sign the hard drive is starting to go bad.
