admin issues

Hi, I installed XWiki standalone on windows. I went in using Admin/admin then entered my own personal details. Now I can�t log in using either Admin or my account details, it always says Wrong User Name. So I uninstalled and reinstalled, same problem. Strangely after the reinstall the welcome message and other characteristics of the virgin installation don�t come back. Is something left in the registry? Any tips please? TIA John