RewriteLock suddenly stopped working!
I'm just putting this here because I didn't find much on Google when
looking around for this issue. Today I had a problem with my 2.0.63
Apache HTTPd server where pages would come out garbled. I'd seen this
before and recognised the symptoms: people were getting each other's
rewrites! Usually this is a sign of a missing RewriteLock directive in
httpd.conf, but mine was there.
After a few false fixes, I think I've narrowed the problem down to my
web server hitting MaxClients. For some reason, it seems that once my
web server exceeded its
MaxClient limit, the RewriteLock stopped being
effective and things went bad.
So there you go. I might be wrong about this since I'm only going off a
single data point and haven't dug any more deeply but, for me, upping my
MaxClient setting fixed things.