Shaun,
Sorry to be thick. I was thinking in terms of whether I'd joined, liked or whatever a Cycle Chat link. I've certainly done nothing to link by facebook account with this site. I think the problem is that CC is now trying to open a facebook page or link each time I open a forum or topic. Websense sees this as an attempt to open a barred site and asks me to confirm - I then have to decline about four times before the message will go away. If I accept I can then see a small part of a 'websense' site barred window in lthe lower part of the screen.
I have the same problem on lots of other sites (including for a while the BBC) and I suspect it's an issue for anyone browsing from work where websense or a similar programme is used to bar 'undesirable' sites.