There must be a virus in your computer.Try to change the name or type
of regedit.Go to C:\WINDOWS\system32 or C:\WINNT\system32,find the
regedit.exe.Change the regedit.exe to regedit.com,double click the
regedit.com,you should open the regedit by this way.
But the solvent is find the virus and delete it.Let Security Expert
help you.
Run Security Expert,go to tools -> process manage,find the backdoor
process,and delete it.Then go to tools->Autorun,find the startup
program of the backdoor,and delete it.The last,find the file of the
backdoor in your computer,and delete it.
Go to
http://securityexpert.cnns.net/download/securityexpert.exe to
download the software.
You can make judgement of a suspicious process easily by this way:
1) Run Security Expert,click Security Tools->Process Manage
2) Choose "Hide windows' process" to help you to remove legitimate
process of system
3) Notice suspicious process with special color marked by Security
Expert
4) Notice whole route of the process is not in "program files"
5) If the process doesn't have information of companyname,the process
possible is a backdoor or a worm.