These last couple days my computer has been having internet problems. It will sometimes disconnect from the internet and kick me off of programs that use internet. Internet Explorer (I use FireFox though) and certain instant messenger programs can't connect to the internet, and I can't run certain installer programs because they say that I have improper internet connection or firewall settings. I've scanned for viruses, cleaned up disc space, un- and replugged my router, and everything else I could. I need any help I can get, please.
I use a cable type thing for my internet if that helps at all.

Try changing the mac address of your router and then reboot the cable modem.

How do you change the mac address? I don't know much about this stuff...

What do I do after that second step?

Just open your Network Connections and show us what there is. I'm fairly sure that mac address stuff is bullshit.

Also, try connecting to your router and look for firewall settings. Open the Start menu and click on Run, then enter "cmd". Next, type ipconfig -all into the black box that appears. Scroll to default gateway, and type the numbers there (with the decimals) into an internet browser. If you have never done this before and it asks for a password, just login with admin and no password. If that doesn't work, use admin for the login and pass, if that doesn't work, try no login or pass, and finally if that doesn't work, look up the default login and pass for your router.