When I start windows xp windows installer pops up and starts sonic activation module. If I say cancel, it starts again,and it is continuous.. how to stop this :confused:

I am not sure whether it's a virus or spyware but download AVG antivirus/antispyware and run a full system scan

After installation, do a system maintenance:

1. Defrag your hard drive. Use the built in XP defragmenter (dfrg.msc)

2. Go to Start->Run... and type or paste "Rundll32.exe advapi32.dll,ProcessIdleTasks". This will start a built in optimization routine that runs in the System Idle Process. If you get tired of it running, you should probably log off or restart to be safe, rather than ending the process.

3. Delete anything that you don't need in the Start->Programs->Startup folder, and in the Registry under HKLM->Software->Microsoft->Windows->Run and HKCU->Software->Microsoft->Windows->Run.

This usually indicates you are loading something in startup that requires Windows installer. Check under Msconfig>Startup for any msi files being loaded. Does it say what's being installed?