I had an issue with Lightroom 1.4.1 that had me scratching my head. When I started it up it gave me a mfc80u.dll error and then closed itself. After a couple of hours of searching I found the cure. Hold down the ctrl key while starting Lightroom and point it to a new catalog. it started after a Windows XP update.
I thought I would pass this along in case anyone else ran into the trouble.