sree chinta, could be caused by a failed Mircosoft update as well as an infected computer. Follow this advise :"Try these methods and check:
I would suggest you to perform a System File Checker scan and check if that help:
This article describes how to use the System File Checker tool (SFC.exe) to troubleshoot missing or corrupted system files on Windows 7.
How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7
I would recommend you to place the computer in clean boot and then check if the issue persist.
A clean boot helps to verify if any third party application services or startup item is causing this issue.
You may refer the following KB article to set the computer in clean boot:
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
Note: Put the computer to normal as mentioned in Step 3 from the KB article.
If the issue doesn’t occur when the Computer is in clean boot, then the issue is confirmed to be caused by a non-Microsoft application.
Run a virus scanner and check:
Virus is known to cause these issues. Scan your computer from Microsoft Safety Scanner, which helps to get rid of virus, spyware, and malicious software.
Note: The Microsoft Safety Scanner expires after 10 days from the date of installation.
Note: Any data files that are infected may only be cleaned by deleting the file entirely, which means there is a potential for data loss." from here. Hope this helps, good luck