I had the same problem today, but was able to fix it. It was due to a problem with missing time zone information in Windows XP. This causes problems with Outlook. I was not able to create a new appointment in Outlook and it kept crashing. Apparently, a while back I ran a registry cleaner and it erased all of my time zone information. You can check if this is the case with your computer by going to Start/Control Panel/Date and Time and click on the Time Zone tab. If you don't see any time zones listed, or the map is incomplete, you need to restore your time zones. Go to
http://windowsxp.mvps.org/timezones.htm and follow the directions. Hope it helps.