If you are testing out Kaspersky Security for Exchange 2003 but decide you want to see how Exchange's built-in IMF works in comparison without first uninstalling Kaspersky Security, do not set the Kaspersky services to disabled, do not pass Go, do not collect $200. If you do this simple step you will bask in an email-free workplace for many relaxing hours until such time that either a) you realize your mistake and re-enable it, b) someone else realizes your mistake and reenables it, c) someone from HR comes by your desk with a cardboard box.
Note: it wasn't me X-)