How to fix a missing uninstall button in Windows XP

I often have the problem that I cannot uninstall some programs in Windows XP. The programs are listed in the "Installed Programs" dialog, but the uninstall button is missing. Today I found a workaround how to re-enable this button:

1. Open the registry editor (Run: regedit.exe)
2. Navigate to HKEY_CLASSES_ROOT\Installer\Products
3. Then locate a subkey where ProductName is equal to the program to fix
4. Within that key, find a path that starts with C:\Windows\Installer followed by a GUID (e.g. {0A869A65-8C94-4F7C-A5C7-972D3C8CED9E}). Most of the time you will find this value in the ProductIcon value
5. Copy the GUID to the clipboard
6. Then navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and check if there is a key with that GUID.
7. If there is no such key, simply add a new key by right-clicking on the Uninstall-Key and paste the GUID (including the { and } characters) as its name. You do not need to add any additional keys or data.
   
8. Now the un-installation should work as intended

I found another explanation on the web that said that sometimes there is a NoRemove key in an existing Uninstall entry. This value must be set to 0.
Note: Use all of the above at your own risk!