So, running Internet Explorer I can browse the web no problem, but lately now when I open up Firefox, I always get that "Page cannot be displayed" error. I'll try to open a simple page like Google or Yahoo and I get nothin' every time.

Not only that, but it's as if I (Maybe I mean, I'm not good at networking) have some ports blocked, because I have a subscription for City of Heroes (a MMORGP) yet I cannot log in because "the login server cannot be found or is down". Thing is, I checked the servers, all of them are up. Plus I can get on with my other computer.

Oh not only that, but I bought System Mechanic 7 the other day. I had 6 and liked it, so I figured 7 would be nice to install on here since it is for Vista. Well, I try to enter my serial number, but it can never send it to them. It's as if I'm not online. But I am, because I can browse around in explorer.

So I'm thinking all of this is linked to one problem, am I right? I can't get a log in on City of Heroes (and no, it's not an antivirus, I unstalled WinClam incase that was it, but it's not, plus I turned my windows firewall off a few times, so that ain't it), I can't send out my serial for System Mechanic, and I cannot browse the web via Firefox.

Now, since I'm kinda a newb when it comes for this networking thing, can any help me out here without using terms or phrases I may not be familiar with? Or just guide me with baby steps? :D Any help is greatly appreciated!

Have you tried system restore -- use the feature to revert your system state back how it was before all this began. I also seem to think there is more to all this than you are letting up, seems like you must have done something to trigger the issue.

Double check connections/Reboot your machine(s) before system restore