Hi Ronda,
I am able to reproduce the issue with VisualStudio 2005 and this seems to work correctly with VS2003.I have logged a bug report in our DefectManegementSystem and we will try our very best to address this issue at the earliest.You can track the progress of bug fix through the below given link.
http://www.syncfusion.com/support/issues/tools/Default.aspx?ToDo=view&questId=1923
As a workaround,you can handle the color change using the Backcolor property of MaskedEditBox.
Thanks,
Anu.