I have read many other questions with similar titles but in our case is Office 2002 SP3, Office XP Pro and happens when using Word as the e-mail editor. It happend right after opening Outlook and trying to create, reply or forward a message.
Surpringly, you can authorize access for 1 minute and work all day. The problem is that Word will hang eventually.
BTX, PC is using XP Pro full up-to-date. All office updates have been applied.