Note: In conjunction with the fix suggested in this article, it's highly advisable to follow-up with a thorough Virus/Malware scan. The problem explained in theSymptoms section may be a result of a virus or Malware attack, or may be a remnant in the aftermath of virus or Malware removal.
Unzip the file and extract the contents (FixDrive.exe and readme.txt) to a folder
Double FixDrive.exe to run it
Select the drive-letter from the list that's exhibiting the problem
FixDrive (for Windows XP / Windows Vista)
Note: In case the problem reappears on restart after running this tool, it's possible that there is a Malware actively running in your system. It is suggested that you run a thorough scan using specialized anti-virus and anti-spyware utilities. This utility does not remove the Malware, but only repairs the settings that were probably added by Malware.