I believe I have discovered the problem. After contacting someone who was having a similiar problem, we narrowed our similarities down to a Netgear FA311 adapter. Luckily, I have another onboard ethernet port that I switched to, and the problem has vanished.
I have no idea whether this is a problem with other cards or specific to the FA311/312 interface card, but for those of you experiencing this, I would suggest you start with your NIC.
