The HPSetup and Free Public WiFi are Ad-Hoc networks (that's what the dot above the normal WiFi symbol means). An ad-hoc network is a wireless network that one computer projects out so that other computers can connect to it. Basically, if a computer has a wireless network card, it can function as a router instead of as a connecting client. This can let you set up networks for WLAN games, move files from computer to computer, etc, when you can't connect them easily. It also lets you share internet. So if your computer is getting internet from a 3G/4G modem, ethernet cord, or something else, you can then set up internet forwarding/sharing to any other connection it has, such as an adhoc network it's broadcasting, so that other devices that connect to your computer by wifi can get internet through it. Sorta like when people tether their laptops to their 3G smartphones to get internet to the computer through the phone, but in the reverse direction.

Now, the hpsetup ones are indicative of HP computers for whom the owner never bothered to clean-reinstall the OS when buying the computers (presumably laptops) or even bothered to uninstall all the bloatware - which makes sense if you're on a college campus. (By the way, I would recommend doing that with every computer you ever buy, because it makes getting rid of bloatware so much easier, and keeps you somewhat sharp on the OS installing skill, which is valuable. But I digress...)

The "Free Public WiFi" ad-hoc networks confuse me more... I thought my campus may have been doing something with WiFi repeaters or something else and they were coming up as ad-hoc networks when I first saw one, but I didn't trust it at first, and the few times I did try to connect to one I never got anywhere. Honestly, I don't know what this "Free Public WiFi" ad-hoc network thing is. It's so randomly common on campus nowadays that my current suspicious is that there's either a virus going around, or some "feature" (hidden or not) in some popular-among-college-students program makes the computer automatically create an ad-hoc network. Since I doubt this is about altruism and free internet for all, I suspect it may be something malicious or annoying-at-best.

I would look that up (I intend to too, but I might not get to it for a bit). If you're feeling like getting into hacking you can see if you can take advantage of these adhoc networks to hack the computers of the people who leave them on... I don't encourage you do anything unethical in the process, but just noting they might make good targets (though I lack the hacking skills to know for sure how exploitable the hpsetup and Free Public WiFi adhocs are by default - average college student's computer though, with default out-of-store configuration?).

Anyway: For whatever reason on the N900, sometimes ad-hoc networks don't go away from your available network list, even if that network isn't within range of your N900. Especially if you've tried to or have connected to those networks already. Rebooting might solve it - typically I go into Settings, "Internet connections", press the connections button, and delete them manually from there. Just don't reconnect to those adhoc networks again (you won't get internet from them normally anyway), or delete them from the connections list manually again every time they get left over in the available connections list.

As for being unable to connect to your university's WiFi, what steps do you take to connect, what exactly does the N900 display when you try to connect, and what do you do after you've connected/tried-to-connect? Does your university redirect you to a webpage that asks for your student nickname/id and password to be able to use the campus wifi? What do you remember installing or updating since you last were able to connect?