Some mail forwarded to Junk folder

Hello,
I have a computer running Office 2003. The problem is that some mail is forwarded to the junkmail folder. I have tried changing the junk mail setting in Outlook 2003 but without success. The junk mail settings are now set to allow all mail (no junk mail filtering, no access lists, etc.)

This problem is only on one machine in a domain of about 75 machines. (XP, Office 2003)

Thanks for your help!