asterisk users - Apr 2005 - SIP calls being lost "frame from cahnnel" error

I've got a rather heated client that's having random drops of calls,
mostly on
transfer from one extension to another.  They got me a precise call that
disappeared on them and I found this message right before the call ended:

"Didn't get a frame from channel" is the 

I've seen some mention of this in the mailing list, but nothing that
indicates
difinitively what happens to cause the problem or how to fix it.

In our situation, we have Polycom 300's connecting to an * server, so
it's not
low-grade harware.  I'm running * 1.0.5.  It's a 1.2GHz Athlon with VoIP
and
only about 3 lines in use, usually 1-2 at a time, so it shouldn't be
overloading the box...

Anyone have suggestions as to where to look for a solution?

-- 
-M

There are 10 kinds of people in this world:
	Those who can count in binary and those who cannot.