Well I am using Chrome and it happened several times, it seems to have stopped now. I also got a strange warning when loading laserpointerforums.com that said something like "This page has scripts from an unverified source". I think it was probably just a temporary problem from one of the ads but it did try to download something that was known to be unsafe. I wish I had got a screen shot of it but I didn't think to do so at the time.
Alan