Comment 34 for bug 35530

I found that this is not necessarily a Linux error per se, but seems to be a BIOS/boot loader compatibility problem (yet, oddly, it worked with Ubuntu 7.10 and whatever Grub version came with the 7.10). The BIOS is old, 2004, when I turned over the box to be used with Vista it too had the same issue on it's boot loader: only a PS/2 connected keyboard would work on the loader, the USB did not. In both cases, Linux and Vista, once the OS loaded it was fine.

I suspect it is a compatibility issue with new boot loaders and the old BIOS.