AB Towers servers are licenced for a set number of connections/sec, and when the number of user conections attempting to connect to AB at the same time is greater than the license conditions, then the server will start to queue the connecton requests until there is a space available to handle your PC's request to be served by this site. This will inevitably lead to delays in servicing individual user requests, and when the site is also dealing with the advert submissions to your PC, as affected by your browser settings, i.e your virus scanning software scans prior to displaying the advert/post, then the site will be displayed as "not responding".
Reset your IE browser setting to "Medium", and clear your cache - Problem explained - However, due to the increasing number of users on this site, at certain times of the week, this may be something the techies & Ed need to discuss, as only they can get the connection & session stats for the site.
Also, please note this usually occurs on weekend Mornings, maybe as more people want answers to the Q&P/Crossword sections???