recovery encrypted file

I’m using a win xp for client and I have a win2k domain. my win xp client have an encyrypted file. when the OS damage I format and reinstall the OS. but I can open the encyrpted file. I already try recovery agent and import the certificate for file recovery. but still I can open the file. when every time I try to decrypt the file the massage box will appear and the massage is access denied. could any one help me ???