wifi issues

Whenever i select a certain wifi connection and tap on the advance wifi settings then tap on to change the IP setting to static or to add a proxy connection, settings keeps on crashing. It always gives me an error ("settings keeps stopping") keeping me from accessing the IP setting and proxy...

Well I let my brother play around on my laptop and he download a huge amount of things emulators, YouTube recording software, etc. And while downloading these he didn't check to see if the download were asking to download unwanted things such as toolbars and other programs onto my laptop, So...