Transparent background color / VS2010

[ALX]

I use a form with a transparent background color (Lime Green) to act as a help page to point out features of the underlying page. When I add a ".gif" image to the help page form, the background color is no longer transparent and the help page completely hides the underlying form with the Lime Green background color that is supposed to be transparent. This issue shows up in VS2010 but not VS2008. Has anybody else experienced this ??? Is there a fix or do I need to go back to VS2008 ???