Registry Editing Has Been Disabled By Your Administrator

Method 1: Using the REG.EXE console tool
1. Click Start, Run and type this command:
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f
You should be able to launch the Registry Editor.

Method 2: Using the Group Policy Editor (Windows XP Professional only)
* Click Start, Run and type gpedit.msc and press ENTER

* Go to the following location:
User Configuration Administrative Templates System
* Double-click Disable registry editing tools and set it to Not Configured

* Exit the Group Policy Editor