It sounds as if your b/band connection is dropping after a while? Next time, run a check on something else - like emails - or look at your b/band modem diagnostics. This all assumes, of course, that you have 'autoconnect' selected for the modem as you do not mention having to 'reconnect' on boot-up? You could also try a 'ping' before you reboot to see if your connection is still there. If it is dropping and your ISP does not know why, then we will need the heavy-weight experts on here.