vb12 cannot find file that is there!!

Hi Experts,

The following code

       If My.Computer.FileSystem.FileExists("c:\windows\system32\drivers\agp447.sys") Then
            MsgBox("File found.")
        Else
            MsgBox("File not found.")
        End If
        End

always messages " FILE NOT FOUND "....but the file is there! I put it!

How can I make it detect it there? in that particular path?
It used to work properly for many years until yesterday that I installed AVG PC TUNEUP and already uninstalled it but even then..

Also used attrib "c:\Windows\system32\drivers\agp447.sys"
and it says it has only atribute 'a'

using it in several win7 stations.... that are still working good...
only this pc is giving me the problema but  I am afraid it may start appearing in the rest.
Regards,