Internet Randomly and Regularly Disconnects?

[Jehrum]

I've been having problems getting my internet to be more reliable and not disconnect so often. It happens dozens of times each day and lasts anywhere from 3 to 45 seconds. Originally, I was with Comcast and wirelessley connected to the router which was in another part of the house. Thinking it was the wifi having trouble getting to my receiver, I bought a power line adapter to directly connect to the modem. I kept having the same issues, so I switched to another internet provider thinking it was Comcast's fault. That didn't solve the problem either. Next I tried disabling my firewall and running some virus scans. Still nothing has changed. So I've come to the conclusion that there must be something wrong with my network settings or the adapter itself.
So my question is, what should be next in my trouble shooting list? I'm not a computer expert, but I have competent enough to follow simple instructions. Any help would be greatly appreciated.
I'm using an Alienware laptop running Windows 7, Intel Core i5 3210M, CPU speed of 2.50 2.50 ghz, and 16 gigs of RAM.