try clearing out the in box of all items - the inbox data base may be corrupt. In fact do a general cleanup.
If that doesn't work try rerinstalling it - back up the old database files first and see if it still happens with a new database - then copy your old database back if all is well.
also try this link
(no help at Google, so here I go)
XP Home, spyware free, etc.
Outlook Express hangs when I click on the INBOX. (gee, the whole issue appeared in the title of this thread!)
Is this a known issue or do I need a tweak?