Unable to start Virtual Machine

Out of the blue, the following error message occurs when trying to start the Windows DB:

"Virtual Machine cannot be started because of the following problem:
Parallels Desktop is unable to access the virtual hard disk image file/users/..../Microsoft Windows XP/Winxp.hdd

The file is used by other application"

Running Parallels Desktop 3 with the latest build on an iMac 7.1 OS C V10.5.4 with 2.4 ghz Intel core 2 duo and 500 gb hd.

Any help would be much appreciated

 

http://kb.parallels.com/en/4938

 

Thanks John. That took care of the problem!