Changes in E-mail protection in NIS 18.6.0.29? Sudden problems talking to the mail server

Hi! I'm using Oulook 2007 as an on-board E-mail client.

Sometime on Fri Aug 13th between 17.13 and 21.51 CST something happened which has led to that I have to turn off the E-mail protection on NIS in order to be able to download and send mails from my ISP. During that time, I didn't do any changes to my computer (running Vista HP (x64) and after checking with the tech guys at the ISP, they haven't done any changes at all. Is there anyone out there that has any suggestion on what's going on? Outook.exe is "Allowed" on the program list.

Thanks in advance!

Peter