Mod_rewrite and its lock file on Apache 2

I'm having a problem with a mod_rewrite program map (which needs a
RewriteLock-defined file) running on a new Apache 2 installation that used
to work fine on an Apache 1.3 install...

The program map is reacting as if the lock file didn't exist (results are
not consistent), which results in the wrong data sent out. The lock file is
defined as being in a read-write dir, I tried several ownership/permission
settings, but the result is the same. I also don't see the lock file itself
when the server is running, although I don't remember if I ever saw it or
not on the old install...

I'm wondering if there's anything that changed between the two mod_rewrite
modules (assuming they are in fact different) and if I missed something.

Thanks for any info...
Seb