I have been having the same exact problems today... It went as far as my NIC not working. Had to restart it manually... Not sure what to think att his point... You do not have Comcast for internet by chance do you? Wonder if they would be cracking down on network usage? Wouldnt be the first time they did that....
Yes, I do use Comcast. I don't think that they would be doing anything however. They learned the hard way about bit torrent [I use it rarely and there are plenty of legitimate uses; for me, that is where I downloaded the latest Debian DVDs for instance]. The amount of traffic generated by miners [and bitcoin clients] would be small. It is not noticeable at all on the usage meter for the month [Netflix streaming alone dwarfs that]. It could be that Comcast is having some issue, but if so, I wouldn't think it would affect so many pools [and seemingly only pools and not their sites] without it being intentional which is why I think it may be a third party [some miners wanting to get ahead before the difficulty increase?], I remained connected to work via VPN for 10 hours straight minus the modem and router reboot to change my IP address. I am reasonably sure that all the DDOS going on over the last many weeks has been from somebody who is a member of this forum or at least reads it.
EDIT: I think it is definitely NOT Comcast. Slush and Deepbit are totally unavailable to me for mining, but BTC Guild IS available, but the miner idles are too outrageous to use [no RPC connection errors however].