huge problem with rootkit

Hello i really need yours help!
I have a virus on mbr that restart my pc every 5 minutes…sorry for my english…
this is the problem revealed by aswMBR

File C:\Windows\system32\drivers\sptd.sys TDL3 ROOTKIT

what i have to do??? thx
ale

Hi SPTD is a legitimate programme unles it has been subborned

Please read carefully and follow these steps.

[*]Download TDSSKiller and save it to your Desktop.
[*]Extract its contents to your desktop.
[*]Once extracted, open the TDSSKiller folder and doubleclick on TDSSKiller.exe to run the application, then on Start Scan.

http://i466.photobucket.com/albums/rr21/JSntgRvr/TDSSKillermain.png

[*]If an infected file is detected, the default action will be Cure, click on Continue.

http://i466.photobucket.com/albums/rr21/JSntgRvr/TDSSKillerMal-1.png

[*]If a suspicious file is detected, the default action will be Skip, click on Continue.

http://i466.photobucket.com/albums/rr21/JSntgRvr/TDSSKillerSuspicious.png

[*]It may ask you to reboot the computer to complete the process. Click on Reboot Now.

http://i466.photobucket.com/albums/rr21/JSntgRvr/TDSSKillerCompleted.png

[*]If no reboot is require, click on Report. A log file should appear. Please copy and paste the contents of that file here.
[*]If a reboot is required, the report can also be found in your root directory, (usually C:\ folder) in the form of “TDSSKiller.[Version][Date][Time]_log.txt”. Please copy and paste the contents of that file here.