Vista - "Time on Task?"

I have had this HP Pavilion computer running Vista Home Premium a little
over a month and am gradually finding which of its many quirks are
reproducible. I only came across this newsgroup a couple of days ago and I
would like to think that I may get some useful tips from it. I will start
with what must be a very simple problem.

On reading through this, or similar news groups, I lose connection after
29 - 30 minutes. This has happened often enough for me to claim that the
effect is reproducible.

I don't see how reading posts qualifies as "idle time", but anyway I have
checked the idle time setting in two places....and get two different figures
which is a second problem. In what I think is the connection to the local
provider (Aliant) I can set the idle time to its maximum of 59 minutes.
In what may be a Microsoft controlled part of the program the default figure
is 20 minutes but there are other options up to "never". Any suggestions
?