OK, double checked everything is in order and up to date on the server. Can't see any issues.
A few points.
1. Advertising is necessary but kept relatively low key. We don't and will never have pop ups.
2. We take security seriously. Please inform me directly if you beleive there's an issue.
3. I have verified popups appear when you click an imageshack link, check this one here > http://www.retrobike.co.uk/forum/viewtopic.php?t=3595
4. Perhaps Neill could try and reproduce the original issue and supply me with as many details as possible. Did you click an external link? Also are you connecting through a proxy?
If anyone else has had any issues please let me know asap.