registry editor

Dependinfg on your OS you will find regedit.exe in different places. Do you have one on your hard drive? Do a search. If you cannot run anything, you may not have rights or you may have had a virus that deleted some of your windows files.

Many viruses close msconfig and regedit as soon as you run them! that is to prevent you from removing them.

It is critical before proceeding is to be virus free.
If you don't have a CURRENT Virus Scanner try
Mcafee's Stinger at:
http://vil.nai.com/vil/stinger/
Then depending on your OS restore rededit if it is truly missing with SFC.
Please include pertinent data when submitting, makes it easier to diagnose.

I have seen this in a running in a quite few Hijack This logs. W32.Gaobot variant
Have a read here http://securityresponse.symantec.com/avcenter/venc/data/w32.gaobot.afj.html As stated above give a run with a online scan find it and kill it,
Of course the online scan may not delete it for you, But it will identify it make note of the location, Reboot to safe mode and delete the file. XP and ME user should disable System Restore first,