Sorry for my confusion, I thought you were reporting an error on burning. I have passed the php error along to Clinton, our site's owner and chief admin.

Brasero is, of course, able to burn ISO files. My guess (and as they say, this is only theory) is that somehow the mixed version approach that Klaus still uses to build Knoppix has broken part of Brasero and that wasn't caught in testing. If I'm correct (and I sometimes am) this is just another example of why I only use Knoppix as a Live CD and never ever install it or install other software into it.