I have a user who is having problems with her outlook.  Now keep in mind that she keeps everything she sends or recieves and yese she does archieve old email. The problem is that hen she trys to send an email with an attachment outlook freezes while trying to attach the document. The top of the window will say "Not responding" for a couple of minutes then finally it will show the attchment is complete. This is the only user who is having this issue.

Any suggestions??

I had a user with the same problem.  What i did was run scanpst on all her pst files.  If even one is corrupt it will hang outlook.

2nd, to make sure that the problem was not with outlook itself i recreated her "outlook" profile.. then mapped her pst back one by one.

 This solved the problem.  Hope this helps.
 

I have seen that before with both opening attachments and attaching them.  I was able to take care of it by emptying out the hidden temp folder that holds the Outlook attachments.  The exact name of the folder varies but can be found in C:\Documents and Settings\<user ID>\Local Settings\Temporary Internet Files\OLKXX.  You can not see this folder in Explorer but can in Command Prompt.  I have had users with several thousand documents in there and once I emptied it out Outlook began behaving itself.

I hope that helps.