No, not using any kind of popup blocker - at least as far as I know. Like I say this problem started a couple of weeks back on a PC I've had for 5 years. It's Win '98 and I'm using internet explorer. I can open the main window, but if for example on one of these pprune pages I click on the "profile" link, a secondary window opens, but stays blank, even after many minutes. I'm using a broadband connection as well, and everything has always been very fast.
The only possible cause I can think of was that I installed a TIFF reader from a CD-ROM given to me from a department at work. Will this change anything ??