Wow....

*Scratches head*

Digging in these things are my fav... dunno if I'll find anything... but I'll look.

One last thing you may try is diggin through the source for mod_proxy and actually setting the "system buffer" useage to 0 also.. (ca't remember where it is or what it is called) and recompile the module using apxs (if that is setup properly too)

One way or the other, I'll report back... might be a bit fer reading/hacking... You too though if you finger it out.

BTW, how big is the payload???