(2-part post):
Hmm.
Are you really sure that you're actually losing your internet connection? Or is it that your computer remains connected but no data is sent to your browser?
The reason I ask is that lots of people have had similar problems recently, where they remain online but their browser can't retrieve any data. If (unlike those people) you're
genuinely being disconnected, I don't know the answer and I apologise for wasting your time. If, on the other hand you share your problem with those people I've referred to, the following solution should work. (Don't ask me why. I just know that it does).
First, find out the primary and secondary DNS addresses used by your ISP. (If your not technically minded, don't let that worry you. They're just strings of numbers, such as 194.72.6.57). If you're with one of the main UK providers the details will be here:
http://www.idl.uk.com/email/isp_settings.htm
(If not, they'll be on the support pages of your ISP's website).