Proxy server changed by itself?

Is there a virus that will change the proxy server for both firefox and internet explorer?

Computer was working fine last night when I went to bed. When I got up this morning it said it had been shut down incorrectly and I couldn't get on the internet. My husband said he used the computer to finish a paper in Word and to check the stats on his football team.

I discovered the proxy settings had been changed to ';manual'; in Firefox and IE. My husband wouldn't know how to do this. I'm concerned that even though the computer is working - something happened and could the something be a virus? And why would a virus change the settings so you couldn't go on the Internet?Proxy server changed by itself?
Maybe your husband was checking other ';stats'; besides football, and was using a proxy that allows him to surf the web via an anonymous proxy. Then, he forgot to set it back? Manual proxy usually means someone wants to specify a proxy by typing in the address/port themselves.

However, if it IS a virus, check what address the proxy is going to. If you use a regular proxy setting, reset it back to that. If it changes back to the unknown proxy again, then odds are something is infected and trying to get your machine to go thru a specific proxy where they can re-direct your web surfing at will. (very dangerous for viruses)

Most people do not use a proxy, unless at a company, or specified by your ISP. So I wonder why you have a proxy at all since this was at home....