As the option to downgrade is in admin CP I used it, and got into same error mess. There was no warning that downgrade was going to mess it up. I chmodded and chowned my lsws conf folder recursively to nobody and that made it work again. I got a really serious server hiccup the other day. something like 2000 lsphp processes were spawned in about a minute, after that disk went to read-only mode, mysql could not release locks and /var corrupted in the end. Disk was FSCK's and I tried to restart service few times - first it looked ok but in a moment the processes went crazy again. Only thing that fixed it was downgrade to LS 4.04. Maybe it happened because I had not updated PHP LSAPI with 4.10, but how do I know for sure? LS Logs did not warn about any configuration mismatches. But in general, a bit older versions feel more stable to me (emphasis: feel). What I would really love to see is some tool to profile server usage and suggest settings and warn about weak points in settings and configuration. Frankly I don't know what half of the settings REALLY do - I have a clue but when running a 24/7 service "to know" would be better.