Strange situation: I recently upgraded my internet speed from a sub-1 meg connection to 10 meg. Nothing else changed - same ISP, same Mirc install, the whole nine yards. But ever since, I'm unable to stay connected to any IRC server. (Well, any of four, anyway - StarChat, ChatSpike, SorceryNet, and QuakeNet.) I connect to the servers as I always do, but after a minute or two, I'm disconnected with a "[10053] Software caused connection abort" error. Rebooted my PC, router, tried different ports, ensured Windows firewall was disabled, all with no difference. And to be clear, I'm a long-time Mirc user and it worked flawlessly prior to the speed upgrade. Currently running Mirc 7.43 on Win7 64-bit.

I know there's at least one other 10053-related post in the forum, but the messages in it go back literally years and offer little in the way of help. I'm hoping that the speed-related specifics of my particular problem will make it a little easier to address.