unable to read the file because its encrypted by windows

Question

Possible Duplicate:
How to restore encrypted files after reinstalling Windows XP?

The hard drive I was using before with Windows XP sp2 installed crashed yesterday, so I got a new hard drive and reinstalled Windows XP. I already have an external hard drive I regularly use for backups and sometimes save directly to it.

I used the same username I had before in the new installation.

My problem started when on accessing a file on my backup external drive, I started to get the error message

unable to read the file somefile.vbproj (this file is a vb.net project file) , access to the path is denied.

I did some checks, and found that the file is encrypted, trying to decrypt it by unchecking the encrypt checkbox did not work.

Does any one know how I can decrypt this file and be able to open it again.