A couple of options you can try to abort Shutdown.
At the command prompt, type shutdown -a
(notice the space between shutdown
This effectively orders the computer to abort shutdown.
Right click on desktop.
In the Location
box, type C:/windows/system32/shutdown.exe -a
Name it abort shutdown
, or something similar
Drag it to the quicklaunch bar.
(you can change its icon if you want, right click / Properties)
Now you have a one click, instant shutdown abort.
Then update your Antivirus, and run it.
Go into Safe Mode with networking.How to start Windows in Safe Mode
Then run these online virus scanners:http://www.pandasoftware.com/activescan/http://housecall.trendmicro.com/
Symantec has manual removal instructions here:Backdoor.Haxdoor.D