I have the identical problem on three boxes:
1 win95->win98 1st ed. w/28.8 sportster
2 win98se w/generic 56.6

After my computers have been running for an
extended time, anywhere from 5 hours to a
couple of days, my internet connection just
sort of stalls and doesn't receive the page
contents or connect to the server. The
browser just sits there and waits for Godot.
Nothing happens, and eventually it times out.
It happens with Netscape 4.51, IE 4, and recent
builds of Mozilla. Disconnecting and
reconnecting to my isp does nothing. Trying
a different isp doesn't work either. I've
tried refreshing Explorer with selecting an
icon and hitting F5 but without success. Two
of my computers have rather a lot of programs
installed, many of which are shareware, but
the third has only a few programs installed,
several of which are shareware, and browsing
still sucks. The only solution is to reboot.
Then, everything is fine. I've disabled
superfluous programs using msconfig in the
startup folder (however Realplayer keeps
coming back!), and this didn't have make
much difference. Anybody have this
experience?

Anyone want to comment on whether or not
too many programs (especially shareware)
causes win98 to buckle? I defrag and do a
thorough SCANDISK regularly.

Hope someone has an answer. I don't really
want to have to reinstall win98 again. I've
read of people regularly reinstalling win98
to keep their system fresh. Seems a little
drastic for routine maintenance to me.

you may have the phone co. look at the lines, there may be something w/ the line connected to the computer and restarting does something to it, I'd say that if it happens on 3 different computers w/ different configurations AND different ISP's, that only leaves the lines. I don't know why the restarting would make a difference, you'd think just disconnecting and reconnecting would work but I've seen some strange things w/ computers so I don't put anything past them. You may check your resources at different times while being connected to see if it slowly drains while being on, because just sitting there will slowly drain them, that may or may not be it. You may wanna call the phone co. and have them check your lines though.
good luck

i used to have that problem, but it would quit communicating after minutes to an hour or two....oddly enough, i found the problem was the cpu...it was an old cyrix MII or w/e...probably not the problem in your case though...

what hardware do you have in these boxes?

I, also, have this trouble sometimes.
I think certain websites plants a bug through java scripts.
Exit your browser and ISP connection, than push ctrl, alt & del.
Look for signs of your browser or something that should not be running and "end-task" on it.