Is it your PC or your Telephone line? I had problems like this, and to cut a very long story shorter, after trying everything else, and with excellent personal visits (free) by three BT engineers at different times, I moved the PC to the main telephone junction box to the house, (rather difficult) disconnected the remaining telephones (four) and started afresh, we found that a line to my kitchen, totally apart from the PC line was at fault. after removing that and buying wireless telephones my problem has never returned.
I then moved my telephone line so that my PC is plugged to the first box into the house. One of the reasons that I stay with BT, their after sales was very good as far as I am concerned, not many others provide a free (3) visit to try and resolve a problem?
even broadband lasted about fifty minutes last night then it just dies - OK its on an old extension upstairs - but unplugging the cables and reconnecting does not make the link work - only a total reboot of computer - anyway have XPCD and am going to look at upgrading see if that helps ???
I get that sometimes too. I rang up BT and they said they'd give us a new router (as they thought the one we have is overheating and causing the connection to stop)...but so far nothing. "3 - 5 working days" has turned into 8 :S