SSII 1000 issues

[bcrichnc]

My network just got a great deal on some old SuperStack 2 switches. It is an older network that was still, unfortunately, using 10Mbps hubs. However, since they scraped together enough money to buy these switches, we now have upgraded to these SuperStack 2 1000 switches, which they're 10Mpbs and can operate at Unit Default, Half-duplex, or Full-Duplex. Everything seems fine on the rest of the network, i.e. the computers with the older 10/100 NICs seem to connect to the network and access all of its resources perfectly fine. However, we just purchases several new computers that have 10/100/1000 NICs in them. Most of the time, these work perfectly fine and connect to the network no problem. There are instances where the user can't connect to the network for a few attempts, and then is able to connect no problem a couple of tries later. After further analyzing this, I noticed that the download speeds are erratic. They go as low as 10KB/s to about 250KB/s. I thought this was a problem with either the switches being in full-duplex mode (no way to put these old switches in auto-sensing) or the NICs on the new computers looking for the fastest possible speed in which they can connect. So far, nothing I've tried has worked. Thanks in advance for any help.