There are several reasons for trouble with Outlook, depending on the content of the mail itself, or the level of the filter. If you are unsure about what you're seeing, send a detailed report, including your version of Outlook, Windows and any error messages you're seeing!

Outlook may be triggering over Words & Phrases violations in the e-mails, eg: if theres a bunch of illicit spam in your box. Try to remove the "Words & Phrases Shutdown" trigger from inside the Activity Consequences section under the System Settings in Net Nanny Settings. Just turn off the shutdown.

Another option is to add the Outlook .exes to the Permitted Application list, especially if blocking Spam isn't a major reason you use Net nanny. Just the the Perm. Application section and add ALL of the Outlook files to the section.

Last, but not least, make sure your Users aren't too highly filtered, eg: leave them at JUST Level 2, with the Content Filtering on. Then try it without the content filtering.

Make sure your e-mail address isn't included in the Personal Information section of Net Nanny.
Make sure you login first before you try to retrieve your mail
Please make sure Outlook doesn't automatically retrieve mail when you bootup. Turn off the 'auto checking' and ask it to wait until you've fully started the machine and had a chance to login to Net nanny.
If the above steps don't work easily, try these steps to re-install:
Remove the software via Start-> Settings-> Control Panel ->Add/Remove Programs -> Net Nanny.
Make sure NO other programs are running. From the CD or the install folder WindowsTempNet Nannydisk1, please find and run the file MDAC_TYP, and if you're running win 98, you'll want to upgrade you installation from this link:

Click here to visit Microsoft's Windows 98 Update Site

and from this link:
http://www.microsoft.com/com/dcom/dcom98/download.asp

Then, reset the computer.

Again, assure NO other programs, especially antiviruses are running and begin the installation of Net Nanny.