Sorry for bumpage, but this had fallen a long way down the forum, and I just realised that one of the last things I did with my working Xorg was install Wine and use it to run Photoshop 4 (I'm poor) and Pro/Desktop (a pretty much unsupported-in-Wine CAD package) - P/D didn't work at all with hardware acceleration disabled, but when I enabled it it presented me with a drawing area (albeit in the wrong place) - however, it got slower and slower, and in the end I had to force-quit it.
Could any of this have damaged my X server?
I just want to get my desktop back...
I fiddled with my xorg.conf in every way I could think of, but the only way I could avert the segfault was by doing things which made Xorg spit the file back at me, saying it was invalid...
I've discovered that if I remove /usr/lib64/modules/fonts/libbitmap.a, Xorg fails to load the module "bitmap", and complains that it's "unable to load required base modules." It then exits - but without segfaulting.
Thing is, I don't think it's the module itself that's to blame, because I copied the libbitmap.a across from my (working) FC4 installation, and tried that instead. It made no difference whether I used the "real" Gentoo one, or the FC4 one - X segfaulted in just the same way.
Has any of this given anybody enough to go on? I still don't know what to do