Unwanted Background Colour

[mrpants]

I work in a small office and use Outlook 2002. All e-mail that I receive from coworkers has a bright pink background. That only happens when receiving e-mail from people I work with. All external mail that I receive has no background colour. When I create messages, there is no background colour. I have no message rules set up and can't figure out for the life of me where this bright pink background is coming from. Any suggestions would be appreciated.