Just to follow this issue up, seems it's actually a bit more widespread than just me....
These all seem to be the same or similar problem over at vb.com
http://www.vbulletin.com/forum/showt...time-out-issue
http://www.vbulletin.com/forum/showt...ts-not-working
http://www.vbulletin.com/forum/showt...-Cookie-issues
Very frustrating that vB.com just seems to be ignoring this problem.