Another computer is unable to access regedit and msconfig

ARGHHHH!
recently very busy to help teachers to clear viruses.
Another computer is 100% infected with viruses.

When I attempt to open msconfig and regedit to do some editing, the programs just closed and nothing happens. After that, when I went into mozilla firefox to search some solutions for enabling the programs. then mozilla firefox just EXIT immidiately!!!!!!!!!!

It seems that something has blocked me from accessing the programs. Any method for enabling msconfig and regedit AGAIN??