Unable to determine computer hardware information with Dell Support Software

Using WinXP on a Dimension 4550.  I don't know why or when this started happening but when trying to check computer information from the Dell Help and Support program, it says "service tag undefined".  If I go to the Dell website and run the "current configuration" from the online support page, it says "no service tag found".  If I start the computer and hit F2 to get into the setup, the information, including the service tag looks fine.

 

I first reported this problem with Dell tech support several months ago and had no resolution so I gave up.  Does anyone have an idea why the Dell software (either offline or online) does not find a service tag?

 

Thanks,

Doug