Unresolved problem

On the first of this month we had switched from Earthlink
dial-up to Comcast high speed internet. Could not believe
the difference. While working on the computer yesterday
morning (everything working fine), I took a break, got a
cup of coffee and relaxed for an hour or so. When I
returned to the computer I attempted to open Comcast and
it would not open. On the IE line where the URL should be
it was completely blank and the toolbar at the bottom of
the screen had the following message "Detecting Proxy
Setting." This was happening on any icon I clicked on if
the site was on the internet (Comcast, Google, McAfee,
etc). Those icon's sites (address book, encarta,
solitaire, etc) which resided on my hard drive opened
fine. It sounded like a connection problem, so I called
Comcast tech support. After an hour on the phone, the tech
said we either a problem with Dell (my computer maker) or
Microsoft and that I should call them. He said the problem
was not at Comcast. I called Dell (got their tech support
rep in India) and worked with him for approximately
another hour. He said he could not determine what the
problem was and that if I gave him my e-mail address and
telephone number he would do some research and, if he
found an answer would call me. I left the computer for
three or four hours and "Lo and behold" when I went back
and clicked on the Comcast icon everything worked fine and
I have not had anymore problems with any sites on the
internet.

Anybody have any idea what happened and if it is going to
happen again. Please keep in mind that I am not anywhere
near a computer guru.

Thanks for the help.

Jackl