Problem being experienced by a number of Notes users

There is this strange problem being experienced by a number of Notes users that I have been unable to get the root cause. These users run into a situation whereby their Lotus notes clients suddenly begin to hang during the process of opening. This frequently occurs when they access some invites or response items. For now restarting the computer is the only solution to this problem.
I also tried reconfiguring the template in the mail file however it produced both positive and negative effects. I am however looking for a way to fix this problem once and for all. I am wondering if this is connected to usernames in the invitee fields or the appending of the domain to each use. As you can notice I am confused and would like your help on this issue.
