See this link from an anti-spyware message board- Spyware Info
It sounds virtually identical to your situation. One of the users suggested a fix that worked. Apparently the reason he had not been able to locate and fix the file was that he had set his “view” mode options for his system set to screen it out as non-viewable.
If that does not work there are a couple of other threads on the topotun malware.
Well, we’ll just keep trying then huh TheLoadedDog 
Might be worth the effort of checking to see if you have Ad-Aware properly configured:
Configure Ad-aware like this then run a scan:
(From the previous link…because I’m a lazy typist)
First in the main window look in the bottom right corner and click on Check for updates now and download the latest reference files.
Make sure the following settings are made and on -------ON=GREEN
From main window :Click Start then Activate in-depth scan (recommended)
Click Use Custom Scanning Options’ then click Customize’ and have these options selected: Under Drives and Folders put a check by Scan Within Archives and below that under Memory and Registry put a check by all the options there.
Now click on the Tweak button in that same window. Under Scanning engine select: Unload recognized processes during scanning and under Cleaning Engine select: Let windows remove files in use at next reboot
Click proceed to save your settings.
Now to scan just click the Next button.
When the scan is finished mark everything for removal and get rid of it.(Right-click the window and choose select all from the drop down menu and click Next)
Restart your computer.
Consider doing a scan in safe mode if possible.
Here is some info on configuring Spybot and Adaware.
Do a search for “spad” and delete the folder. I just did this yesterday and it worked. I think it was simply c:\spad