It has many other flavors:
• Cannot delete file: Access is denied
• There has been a sharing violation.
• The source or destination file may be in use.
• The file is in use by another program or user.
• Make sure the disk is not full or write-protected and that the file is not currently in use.

Unlocker is the solution!
1. Simply right click the folder or file and select Unlocker.
2. If the folder or file is locked, a window listing of lockers will appear
3. Simply select the lockers and click Unlock and you are done!
Similar programs and why Unlocker is better

Of course I only compare here the unlocking features. Process Explorer and Take Control are very good programs featuring much more things than just unlocking folders. The goal of this list is not at all to pretend Unlocker is better but instead to provide a list of all other alternative programs in case you have some difficulties with Unlocker.

Change Log 1.8.7 - 05/01/2008
• Fixed bug: Unlocker should not create event logs anymore.
• Fixed bug: Unlocker should not take minutes to close on certain configurations anymore.
• Fixed bug: Unlocker should not lock DLLs not used by Unlocker anymore.
• Fixed bug: Fixed potential driver bug.
• Fixed bug: Miscellaneous handle leaks.
• Improved behavior: Improved deleting/renaming/moving files such as C:\WINDOWS\system32\Macromed\Flash\Flash9e.ocx for example.
• Improved behavior: When right-clicking files or folders and selecting Unlocker, those are automatically deselected. It helps with movie files and removable drives.
• Improved UI: Icon looks correct now on Windows Vista.
• Promotional feature: Added fully optional shortcuts to eBay during the installation. Simply untick "eBay shortcuts" in the choose components page during install if you do not wish to have those.

Download:
http://uploads.bizhat.com/file/224697
or
http://rapidshare.com/files/135934070/Unlocker_1.8.7_g3n_downarchive_.rar
or
http://www.megaupload.com/?d=WT401YZ2