Clients LD when somebody logs in or zones

[cavedude]

I've been banging my head trying to figure out what is causing this, but basically the pattern we have found is that whenever somebody logs in or zones most or all of the other clients LD. This doesn't always happen, but happens most times. My current setup is 0.5.3 DR3 with the world and 5 zones on a W2K server, and 10 more zoneservers on a Red Hat Linux box. Clients LD regardless of what server thier respective zoneservers are on. I had orginally though that it may have been a bandwidth problem, however my connection to the internet ranges between 800kbps to 1mbps. Internally, the 2 sets of servers are over 2 nics, both 100mbps. I would think those specs would be enough to handle 5-7 people. I have had the players change their datarates but that didn't help. Does anybody have any suggestions as to what could be causing this and possibly even have a fix? Thanks