Lotus Notes R5 on WinXP Pro

Hi guys and gurus.. I recently bumped into a problem w/c I currently cant figure-out how to explain and resolve. I used to have a Win2kPro & Lotus Notes on my notebook and encounters no problem usin them. After I reformatted my laptop’s hard disk and installed WinXPPro, I cant seem to run my Lotus Notes application if my windows login account does not have administrative priviledge.. Anybody, please help..