Problem Syncing Public Tasks

[Ripstah619]

I have a client that is currently on an Exchange server. We have a
Public Tasks Folder that are accessed by three people. Everytime one
of the three users updates a task, everyone else is supposed to be
updated immediately. At least that's how it used to work. Now there is
one person who is not being updated right away when a task is updated.
The other two are but this one user always has to close his Outlook
and reopen it for the updates to take place. This didnt used to
happen. All three users have owner permissions on the Public task list
(which they all need). Since it's only not working for one of the
three users, I'm guessing it's a problem on the client side. I just
need to make sure. Any help would be greatly appreciated. Thanks in
advance.

 

[Ripstah619]

After some more testing I found out that this only happens on this one
computer. I logged on as the user on another computer and it worked
fine. Could this possibly be caused by some sort of virus?