If this is also WinXP, then go to C:\windows\prefetches and delete everything in there.
Scandisk and Defrag your hdd.
Delete all Temporary Internet Files, ~*.* and *.tmp.
Please know that anytime you open an attachment (depending on the size of it), if you do a Ctrl-Alt-Del and look at Task Manager -- it will always show "Not Responding" until that attachment is open.
If the hdd shows activity, Outlook XP may still be processing the "opening" of this attachment. In other words, wait it out -- make sure the hdd activity is none before you think that Outlook has hung.
How long Outlook takes to open an attachment depends on available hdd space, size of attachment, size of current PST file (if opening from PST) or server transmission (if opening from the mailbox on the server), etc.
Please know that while 2 GB is the upper maximum for a PST file, they have been known to get corrupt anywhere around 500 MB. Scanpst.exe is an Inbox Repair Tool that can be used to fix or repair some of the problems with a personal folder. Create several PST files if needed to get your files do to under 500 MB each if necessary. Compact your PST files after deleting e-mail from them.
