After spending all morning messing with connectivity problems, I would strongly advise users of BEFSR11 and older BEFSR41 (Ver 2) routers to NOT be tempted to install the latest 1.45.7 firmware from the Linksys site - caused me major problems, including very sluggish web access and mailwasher not working.
A search on the net shows many people are having problems with it, and reccommend reverting to 1.44.2 Older versions are hard to find on the linksys site -
They can be found here
If you are having problems that you were blaming NTL's general crapress on, and are running 1.45.x, I'd strongly reccommend you try the 1.44.2 firmware (remember to keep a note of your MAC clone adderess and other settings as these are cleared after a firmware upgrade).
Interestingly I've only noticed problems recently, although I upgraded my router quite a while ago.