Take a look at this posting, it's filled with a lot of useful info. Let me know if you have any problems figuring it out.

http://forums.us.dell.com/supportforums/board/message?board.id=pes_oms&message.id=6357&query.id=5363#M6357

Here is another way of doing it also. I have ITA 7.2 and clear the message by right click the machine name in ITA, select app launch and run client console. Login to the machine with the proper rights. Once logged in, click on Configuration, then SMBIOS settings, then SMBIOS settings again, and then clear the Chassis Intrusion setting.