Some emails not getting through
 

I was usng outlook 2002 and I found out that I was not recieving just a few
of my emails (from various senders) and that the sender was not receiving any
returned mail. I originally tried to then receive my emails through outlook
express instead but the same problem was happening. I rang my service
provider and was issued with a new user name. This has not fixed the problem
and the only idea the service provider had was to ring microsoft who
suggested I uninstall and reinstall outlook. Is there any other reason for
this to be happening?