I was using Internet Explorer recently to check the route to the Cribb's Causeway shopping mall at Bristol, UK. I have used the Hotbot search engine since it was highly recommended in one of the very first issues of ComputerActive magazine (around 10 years ago), and I entered the search target simply as "Cribb's Causeway". I selected a likely-looking entry in the list that appeared, only to find the results page of another search engine. I hit IE's Back button to return me to Hotbot (without clicking on any of the links), but instead found myself staring in disbelief at a page of pornographic images, headed "Women seeking men". I then tried to go back by selecting Hotbot from the list displayed from hitting the small down-arrow next to the Back and Forward buttons. I was even more amazed to be taken to a page that told me my computer was riddled with malware, which I could remove by downloading software called MalwareAlarm. I declined this offer and instead scanned my PC with AVG (which confirmed it had no viruses), followed by Spybot and Ad-Aware. These found the usual crop of undesirables, including a cookie from MalwareAlarm. This latter, it told me, would declare exactly what I had seen, finding many false instances of malware that could only be removed by purchasing a licence for the software!

So, first and foremost, don't be fooled if this happens to you. Always be suspicious. But also, how on earth did a page of search engine results hijack my browser like that? I finally got my directions to Cribb's Causeway, but I had to restart IE - and for good measure I also restarted my PC. Surely this highlights a serious hole in Microsoft's security?

A further thought is this: if it happened to me, it could happen to a child using your computer. Take sensible precautions!

   Some sites like that do not let you close your browser or leave their site.  When you do, they put up another window.
   Sometimes if you right click on the item in the Taskbar and select Close from the popup menu for each open browser, you can get out of it.
   If that does not work, restarting your computer (as you found out) will take care of it.
   The MalwareAlarm cookie will not do anything unless you return to that MalwareAlarm ad (then it will not necessarily do anything, it will just provide that ad with information, like that you have already seen the ad).