qemu isapc was known broken for a long time upstream AIUI. I think things got better with the recent 1.1 release but I haven't confirmed. But the dev's were aware and yet it wasn't fixed for a while, so it's a pretty low priority for everyone.
If you can still reproduce with upstream, I'd recommend just filing an upstream bug, since tracking it in fedora likely isn't going to accomplish much:
http://wiki.qemu.org/Contribute/ReportABug