Hi there, I'm new to these forums so firstly thanks for reading my post!
I'm having 2 irritating problems at the moment I really could do with some help with, I'm not sure if they are connect but they're doing my nut

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1) Sometimes I can't access the web. By this I mean that when I have an internet connection over my WLAN I can use programs like MSN, Ventrillo (3.0), and various computer games such as World of Warcraft which are connected to the internet but when I open a webpage using either Internet Explorer or Firefox it claims it can't find a server and won't load anything! This seems to occur randomly and comes and goes randomly, systematically shutting down every possible program on my processes list doesn't help.
2) Under my list of network connections I have a "Local Area Connection 3: Network Cable Unplugged" listed as using an NVIDIA nForce Networking Controller. If I try to disable this connection, repair it or uninstall the driver my PC auto restarts (Basically touching it in anyway kills my computer). I'm really not sure what's going on there, currently I'm trying to install a new driver for it but there are no details on what model it is.
For background info, I took my PC to a repair shop a week or so ago due to my harddrive starting to fail, they stuck a new one in, reinstalled windows and all my drivers. I'm guessing they screwed up somewhere? Anyway, thanks in advance, all help welcome.
Rich