In the last week or so clips on YouTube and the like have kept stopping and reloading every ten seconds or less on my iMac (3.06 GHz, 4 GB RAM, running 10.6.4). This is despite a fast ADSL2+ connection and very fast Safari operations. My MacBook Pro, using the same OSX and the same wireless internet connection, does not have this problem. I wondered if it could be a browser problem, but exactly the same thing happens with Firefox. I've recently installed 10.6.4 and Safari 5, but the browser doesn't seem to be at fault and the OS is the same on both machines. Can anyone suggest a possible cause and, better still, a possible solution?