Process Guard Help *Read!*

im having trouble with a program i have called DiamondCS Process Guard v 2.000. when i try to install i get an error:

C:\WINDOWS\System32\drivers\procguard.sys

An error occured while trying to replace the existing file:
DeletedFile failed; code 2.
The system cannot find the file specified.

Click Retry to try again, Ignore to skip this file (not recommended), or Abort to cancel installation.

* okay so i tried going into windows/system32/drivers and i found procguard.sys, but i cant delete it, do to this error:

Cannot delete procguard; Cannot find the specified file.
Make sure you specify the correct path and file name.

*PLEASE HELP*