Nope, I don't think it's because of some download/update because I have 2 Win7 installations and only one has this problem. And it's not caused by Quicktime either, I don't have it installed.
Adobe PDF version 9 install is fooked on '7, however version
8 work fine. Perhaps the common factor is Adobe? ... anyone remember the dodgy first version of Safari on Windows that leaves me with the concern that they don't always conform.