A couple of suggestions..

1. Download, install, then update the free antispyware program from the link below. Once that's done then restart the computer into Safe Mode and run a full system scan with the program:

Ewido/AVG Antispyware 7.5 Tool

2. I haven't seen this spyware on Vista and therefore, I'm not sure of it's exact file location, but the instructions below should help you remove the problem after editing the registry and manually deleting the file:

http://spyware-removal.thrcomputer.com/how-to/remove-dssagent.html

Hope this helps.

Grif