Thought I'd share a few quick tips to keep you off the cable modem support lines.
First, if you're having connectivity issues, try running a tracert from the command line to see if you can even get to the network.
For those not familiar with how to attempt this, click on the Windows START menu and type "cmd" in the search box and hit enter. This will pop up a command line window, don't panic, it's easy to use. Type in "tracert example.com" for instance and hit enter.
If it tells you it can't resolve the domain name, assuming you typed it in correctly, either you're completely disconnected or your cable company DNS service is down. I have OpenDNS set up as a DNS alternative for those rare occasions when the my ISP's DNS servers are failing, happens now and then.
Sometimes the DNS still resolves the domain name but the tracert times out at your IP address, goes nowhere.
Here's a simple trick, pick up your cell phone and go to a site like [network-tools.com
...] and use their tracert or ping and try to access your home IP address from outside your cable network.
If you can't reach your home IP address via this site, you have real problems, call the cable company now. :)
However, if you CAN reach your home IP address, it's probably just a simple issue with your cable modem and/or router.
Now try the following:
Usually I try rebooting the browser first, sometimes the browser goes nuts.
Then I try rebooting the computer next, and if that doesn't work, I reset (power on/off) both the cable modem and router to see if the problem resolves itself. I reboot the computer before the modem/router so everyone in the house doesn't start yelling about lost connectivity just in case I'm the only one having a problem as you know how cranky people get when their Netflix movie suddenly stops working!
If I'm still disconnected, my last attempt is to try a DHCP release and renew from the modem and/or router, assuming you have a separate router.
As a Comcast customer, I grab the cell phone and tweet to Comcast support people and just ask them if they know of any outage in my area which usually gets a response in a minute or two. If they have no information, then I know I'm in trouble and it's time to call the cable company and sit on hold forever.
Hope that helps some as self-diagnosis of a cable problem, using my cell phone to check connectivity from the outside, has gotten me back online in 5-10 minutes instead of waiting on hold forever and it's been years since I've actually had to deal with the inept front line support people.