Unable to uninstall sneak preview

I installed the sneak preview of NW '04 on a laptop, but now want to remove it. When I select the uninstall option within SAPinst it returns with an error:

FSL-01027 Account user="<domain_name>\<user_name>" does not exist.

Now I am logged on with the correct user and domain and the user has full admin rights and is the same user I used when installing originally.

Can anyone suggest how I can get past this point and remove the software?