Confirming.

Thank you, entered as http://www.ventismedia.com/mantis/view.php?id=5336
and will be fixed in the next release.

Yes to both questions. In fact, if I choose to create a cd/dvd, MM asks me if I would like to erase the data from the disk. When I reply "Erase disc" , it erases the disk and writes without problems.

The problem is only with the "Erase CD/DVD" radio button selection on the "Disc Burning Wizard" window.
When I press "Next", I am presented with options: Drive; and "Quick erase" or "Normal erase". The "Erase!" function is disabled on this window. The button is greyed out, and the "r" shortcut key does not work.

Do you have a disc with data on it, are the disc and the cd drive compatible with Rewrite (RW)?

The "Erase!" button never gets enabled in the "Erase Disc" window of the "Disc Burning Wizard".

I am using beta version 1224, but I noticed this in previous beta versions as well.