Sounds like a memory based greyware that has been installed. What is the name of the file "Main file" that get's caught?
Try the following and let us know.
Download CounterSpy
1.Once Counterspy has done scanning, The 'Scan Results' Box will appear.
2.Click on 'View Results"
3.Under (Remcommended Action), Using the frop down arrows at teh side of each entry found, Set to EVERYTHING to "Remove"
4.If it promts to remove or take action, Click on take Action.
Download Ewido Anti Malware v3.5 from here
http://www.ewido.net/en/download/
1.After download, Double click on the file to launch into install process.
2.During installation, under "Additional Options" uncheck background guard" and Install scan via context menu".
3.The program will promt to update "Hit yes"
4.Click the Icon on your desktop
5.On the left side of the main screen, Click on update" and then click "Start Update".
6.After they are installed, You well see the successfull in the lower left corner.
If you are having problem with the upgrader then maunually update here
http://www.ewido.net/en/download/updates/
Once the updates are installed do the following:
1.Click on "Scanner" and choose "Settings"
2.Under the bottom section "What to scan?" make shure every file" is selected.
3.Select "ok" and you will return to scanning options.
4.On the main screen click on "Comlete System scan" to start the scan.
5.While the scan is in progress, You will be promted to clean the first infected file if found. Put a check next to "Preform action on all infections" in the left corner.
6.Then choose "Remove" and click :ok"
This well take some time but it works trust me......