Kwokwai,
Let's face it: if you don't know about your computer, how could anybody here know more? The symptoms you describe in this post (I didn't have a look at your other ones) are so general, that nothing definitive can be said.
If you put ALL your problems with this machine in ONE post in the Computer Help forum, there might emerge an idea of what's wrong with it. There's ample choice: hardware issues, BIOS-settings, Windows settings, incompatible software, malware (viruses, spyware, trojans). Sometimes a new motherboard is the solution for a lot of troubles, sometimes a clean install of the OS, to name two possibilities that attack a lot of rather vague problems like this.
Not being able to burn a DVD can have a more than one reason. The usual is a low quality of the DVD or just a general incompability between the DVD and your burner. Try another one or try another brand altogether. It could also be that the burner needs to be replaced or cleaned. But I think it's possible that some form of malware of an unexpected entry in the registry can cause it also.
Anyway, I don't think it's a Nero problem. With me, using another DVD generally solves the problem of nero just hanging at 10% or 87% or whatever in between.
But you can try the free CDBURNERXP program to see if that makes a difference.
I don't see why you didn't yet try the advice given to you. It's not so difficult to try it first thing in the morning, or first thing coming home from school, I'd say. And if you suspect Nero, uninstalling and reinstalling is the appropiate action.
Hope this helps.
Kees