What a lot of helpfull comments! I have found in the past week or so (using IE7), that a site called uk.hosting.adjug.com is causing this problem, and, if you google it, you'll find it is affecting many other club sites. Unfortunately I can't open your thumbnail as opening attachments is one of the things that cause my pc to hang up. It only seems to happen on this site for me. Could it be made worse because it is a very big site? I belong to another, smaller, club, where I don't have this problem.
The answer may indeed be to swap to another browser, but it works ok on everything else. I may have no choice soon as IE7 is almost obsolete, but I can't upgrade to IE8, let alone 9, on my old machine.
I have been hoping that the various clubs' webmasters might get together and solve this for us all. My Landy is 38 years old - why can't computers keep going for more than a couple of years?