Hi surajbgl,
Disclaimer:
Before I go any further, please note that I am not an HJT analyst and that for detailed analysis you will need to submit this file to a specialised forum. Should you decide to do this, please keep us informed here in this thread about your progress.
End of disclaimer.
I have had a look at your HJT log and there are a number of serious issues in it. A number of important system files appear to be missing. Some of the important ones are as follows:
1) alg.exe Application Layer Gateway Service
2) lsass.exe Local Security Authority Process
3) slsvc.exe Microsoft Software Licensing Service
4) spoolsv.exe Spooler SubSystem App
5) ui0Detect.exe Interactive services detection
In view of these errors, the best suggestion that I can make is that you reinstall Vista and make sure that you use upto date anti-malware programs at all times.
Dwarf