asterisk users - Jan 2009 - DTMF queuing problems

Hi,
Using rfc2833, I constantly have the problem that if a user presses
digits reasonably fast,
I will see a bunch of DTMF end emulation of 'X' queued on SIP/xxxxxxxx.
This queuing screws up the DTMF because the digits never get sent!
Is there a way to prevent asterisk from queuing DTMF? Or at least make
it a lot better?

Thanks.

-- James