This two methods I discovered on Ramesh’s troubleshooting Windows site – windowsxp.mvps.org.
Type this command in Run box and press Ok.
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f
Using Group Policy editor. Once again in the Run box, type gpedit.msc and press Ok. Go to User Configuration-Administrative Templates-System, double click Disable registry editing tools and set it to Not Configured. Exit Group Policy editor.
UPDATE: Start your computer in safe mode with command prompt and type the following command to enable registry editor:-
reg delete HKCU\software\microsoft\windows\currentversion\policies\system /v “DisableRegistryTools”
and run HKLM\software\microsoft\windows\currentversion\policies\system /v “DisableRegistryTools”
After you have run both commands your registry editor should be enabled
Found this on Rahul’s website. It was showing others how to remove Brontok virus actually, but since Brontok too disables the Registry Editor so it’s worth a shot. 😀