We have a 5port Gigabit switch connecting 2 machines to our Windows SBS 2008 network. 1 client@100 Mbps, and 1 web server@1000 Mbps. We keep having to reboot the switch daily for the client to maintain connection. Every time we do this it works fine for quite a while (0% packet loss), but gradually starts dropping more and more packets. (This is after it works fine for most of the day.) We've tried several brand new Gigabit switches, some work longer than others, some barely work at all (for the client). The web server is not being used due to this problem, so it has no traffic. It is on and connected to the switch though. I changed the speed on the web server's NIC to 100, seemed like that might have helped some, not sure though. I thought it may be the cat5 between the 5port and our 24port Procurve 1400-24G (J9078A) switch, but it seemed strange that the connection would be fine for so long if the wire was the problem. Running a new cat5 would be a major pain at that location, so we don't want to do that unless we absolutely have to. Using a tester indicates the cat5 is fine. (I believe it's actually cat5e, but I'm not there at the moment to verify that.)
FYI:The small switches we have tried have mostly been Cisco SD2005 and Trendnet TEG-S50g 2.01
Most of our SD2005s are grey w/black on front, but 1 SD2005 is all grey and bigger than the others. This one I ordered for home use, and brought it to work when this problem started. It never had a single problem, so we used it while we waited for new switches to arrive. I changed it out with a new SD2005 straight from Cisco, that didn't work, I hooked mine back up, and suddenly that one didn't work either.
Sorry this is so long, but I figure diagnosing without being here is difficult, so wanted to give as much info as I can. I appreciate any ideas anyone has.