EDIT: Problem resolved, by reinstalling it about fifteen times until it finally worked.
Secondlife is crashing on startup every single time I try to run it, and it hasn't worked in about two days. Whenever I try to run it, it gets past detecting hardware and the Secondlife window appears momentarily and then disappears. Just the outline of the window and the titlebar, too, no background or login screen. Never changes. If I try it again, I get the same problem endlessly, only with crash report popups.
I tried reinstalling the client, which used to help this problem in past versions. It didn't this time. So I uninstalled, cleared cache and temp, reinstalled. Didn't work. So I uninstalled it, deleted registry keys relating to Secondlife, cleared cache and temp, and reinstalled, but even then I get the same problem.
I was running the Omega drivers on my Radeon 8500, and that worked fine in SL, but I uninstalled them anyway and replaced them with the normal Catalysts, but that made no change. I also have an nForce mobo which reputedly has problems with ATI's smartGART config, so I uninstalled smartGART, but that did nothing. I repeatedly reinstalled SL during all the configuration changes, but the problem remains. I have no hardware problems that I know of, everything else but SL seems to function properly.
This is baffling because it just spontaneously stopped working. Nothing changed, and it's nothing in my cache. I could run the latest version of SL a couple of days ago, but then it just decided not to work ever again. Removing every trace of SL and reinstalling it does nothing.
I sent an error log as of last night, and looking through the logs I see nothing of interest. There's solutions for problems like this on the Wiki and Tech Support, but they all relate to bad cache files, which can't be my problem as I have no cache and I have downloaded several copies of the SL installer, so it's not a bad install.
This is getting extremely frustrating, and it makes absolutely no sense. If anyone has a new idea, I'm all ears.