HTC Desire :: Phone Won't Start

I hope this is the right place to post this.I am using an HTC Desire running Android 2.2 from the Telus OTA update.I wanted to see the OS without the Sense UI so I went through Settings/Applications/Manage Applications select 'All' selected HTC Sense and hit the 'Clear defaults' button, it did nothing when I went back to the home screen, so I went back and 'hit 'Force stop' the phone restarted but was still using the Sense UI so I shut it down and tried to restart it immediately after the screen went black.The phone then vibrated 4 times in a row and did nothing. After that the phone would not start. The only thing I could do was remove the battery for a few seconds put it back in then start the phone up. Now I find the phone has an issue where if I don't give it a few seconds after shutting down it will do the 4 vibrates and then do nothing.The 'Clear defaults' option in the Sense UI is now always blocked out so I can not select it.Has this happened to anyone else? Is the vibrating then becoming a paper weight an issue due to the Sense UI issue or is that normal because I may not be giving it enough time to shut down or something?