RDP randomly pauses but doesn't lose connection

Looking through here so far, haven't found anything with this yet. Googling
gave me a couple ideas for disabling the autotuning feature in the IP stack,
but that doesn't seem to fix this either.

RDP into any end point - XP Pro, 2000, 2003 server, and randomly the sesson
just totally locks up for up to 5 seconds or so, even though everything else
network-wise continues working, downloads are actually proceeding and
incrementing during the RDP pause, so it's only the RDP client that's
impacted, not networking in general.

Tried combinations of all sorts of options, resolutions, settings, etc. This
happens for myself and three other vista users in our offices.

Any suggestions?

Thanks


--
John