Internet not working on my HP laptop running Windows 7

I first posted this in the malware forum, but Chaslang doesn't think it's malware and suggested I come here.
A few weeks ago, I was stupidly running Torrent software on my laptop (running Windows 7) when I suddenly lost the internet; I would get messages that said the browser couldn't connect to the web page (tried both Explorer and Firefox). There were connections available in the cloud, I just couldn't connect to them. I have since uninstalled the Torrent software.

My desktop PC lost its internet at the same time; I'm going to post that under a separate thread; I mention it here just in case it provides more clues. My desktop is linked to the internet throught my parents' ethernet connection, and their PC still connects to the internet. I've got my desktop internet working only by always selecting the last configuration that worked at startup. Even then, it works okay for a couple of hours, then stops working. It seems suspicious to me that they both stopped working at the same time even though they connect to the internet differently.

But back to my laptop: I found some similar internet connection threads on here that suggested to check all connections and settings to make sure they are set up properly and they were.

I mentioned the problem to the IT person where I work and she offered to look at it. Oddly, the internet worked fine for her when I brought it to work, but she ran something (I think it was Norton), and it worked for her again. So I brought it home and it didn't work there.

So did everything in the "Read Me First" thread in the malware forum and the internet worked fine after that, but it stopped working again the next day.

When Chaslang said he didn't think it was malware, I tried calling our internet provider, and he talked me through a lot of tests and fixes that involved the command line and got it working again (after about 45 minutes on the phone). But the next day, it wasn't working. In fact, the cloud connection that I usually use to connect ("linksys", which is the name on my parents' router) is now completely gone. Formerly, I could at least see it, and it said I was connected (even thought I couldn't connect to anything), but now it's not even there.

Chaslang and the IT person at work keep saying they think it's a firewall, but why would a firewall suddenly start causing me problems when it never did before? And how could a firewall keep changing its own settings after someone fixes it?

Please help. I really need the internet to practice software I need to know for my job. I bought a subscription to Adobe's cloud and if I can't use it, I'm just flushing money away. Thanks.