MIRC Version 6.03 (Registered)
When using a standard jpg/bmp background for all windows, - if you have a query window open, along with one or more channels, when you open up a dcc chat window, the background of the query window will lose its background and revert to the default background color you have selected..
This is a repeatable bug, - atleast for me. It's been there since 6.03.
Cheers
-IvanT