I just upgraded from R5BXX to R5F27, and it did not go smoothly. My PVR 150 isn't working, but I'm not even going to address that until I can get X up and running. As root, I can startx and everybody's happy. As mythtv, I get into a deadly respawn loop ("...respawning too fast..." error). I think I may have shot myself in the foot -- I xrandr'd after initial setup, to what seemed a safe resolution. X started at 1280x1024, and I xrandr'd to 1024x768 -- should have been fine, no? Guess not. Anyway, this was after initial setup had completed.

I looked through my Xorg.0.log, and there's no errors. The only warnings look harmless -- I can post the whole mess if need be. I'm not sure what other info would be useful... it's an old box, the video is on a Radeon "VIVO 64 MB", which I think is a 7200 chipset. It's using "radeon" as the driver. I commented out a bunch of modelines in the xorg.conf to reduce the number of bad modes it could try, but nothing has helped so far.

I'd really like some guidance on where to look next when troubleshooting...

If anybody cares, I "fixed" by moving all mythtv's hidden files to a new subdirectory, then moving a few back selectively. I'm still not sure what file was causing the glitch -- I don't have much motivation to find out...

Most likely you roached the permissions or ownership of some of the files or directories. Moving the old ones allowed them to be recreated with the proper ones.