How To Enable Regedit
If you get the error saying “Regedit has been disabled by the system administrator” when trying to use the Windows XP registry editor, fear not. There is an easy way to re-enable regedit.
Click Start -> Run… and enter this command (all on one line) :
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f
You may need to restart your computer for the changes to take effect.
In case your Run… menu has been disabled and you can’t use the above method here’s another way to make regedit work. Download regtools.vbs (by Doug Knox) and double-click the file. If everything goes well you will get a message box saying “Registry Editing Tools are now ENABLED”.
If the above tricks didn’t help and you still can’t access regedit then your computer is probably infected by a virus or spyware that is repeatedly disabling the registry editor. You will need to get rid of that malware first. Take a look at Spybot S&D (freeware) or Ad-Aware (shareware) for possible solutions.
Random rant : Yes, pretty much everyone “advanced” user knows how to enable/disable regedit or the task manager. I wrote this post not as a revealing of arcane knowledge, but as a test of… well, surely you can guess that. Or maybe I was just lazy and there isn’t much hidden meaning to this random tip 
Your suggestion worked. Thank you very much.
For anyone that is still having problems after running the above fix, try also running the following:
REG add HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f
While this should be obvious to anyone who’s worked with the windows registry a fair bit, it’s worth noting none the less.
Thank you! That’s awesome!