Not sure if this will solve your problem but one thing you might check is this:
Go to Tools>Options>Preferences tab and under the Email section click the Junk Mail button. Under the Options tab and in the section that says, "Choose the level of junk email protection you want,"
make sure, "Low: Move the most obvious junk email to the junk email folder"
Also, make sure the box that says, "Permanently delete suspected junk email instead of moving it to the Junk Email Folder"
Its possible that your Outlook is viewing all your emails as junk mail and deleting them immediately instead of saving them to your inbox. Also, you didn't mention what version of Outlook you're using so the instructions here are for Outlook 2003. However they should be similar for both Outlook 2000 and 2007.
Hope this helps
Edited by malware_terminator, 23 October 2008 - 08:56 AM.