I know quite a few people on here also make use of TBB's Quality Monitor so can you check it and see if yours also shows complete packet loss for a four hour period starting at 2AM this morning?
If it does then it's obviously their problem but if not then my connection was down.
No problem showing on mine.
I think I've worked out what it is.
I'm using a new Linksys WRT320N router and the period of complete packetloss coincides exactly with me switching my PC's off overnight. Although the modem and router are both left on 24/7 it seems the router detected no devices were attached/turned on and decided to stop responding to ping requests. Power saving feature maybe?!?
As good a guess as any, Griff.