Another suggestion (though maybe a futile attempt at straw clutching)...would be to turn off the Modem, router and PCs for between 5 and 10 mins (to let them settle and cool down). and turn them back on again after in order of modem <wait to settle> router <wait to settle> PCs.
When i first got my VM (then telewest) I had the same issue with a WRK54G router but all was ok when directly connected to the CM.
I just left it for a bit tried again (but still didn't work) so i left it on over night and hey-presto it was sorted.
Though I think I could have been at fault that time
---------- Post added at 14:27 ---------- Previous post was at 14:08 ----------
After catching up on the other related threads both here and over at digitalspy...I am inclined to agree that somewhere something has been changed, for this to suddenly happen to various VM BB customers (presuming your all in different areas??).
I don't have any ideas as to what VM may have done for this to happen though...