Sudden error message regarding not finding Proxy server

[#1]

Hi,
some random messsage staeted coming up on my sons laptop on IE and Chrome every time he tries to load the internet, along the lines of, we cannop find/locate etc. Proxy server.  This isn't soemthing we've enabled by choice so before i cerate havoc do anyone have any advice or past experiecne on this.  AFAIK it was fine 2/3 days ago.  He hasn't downloaded anything that he can remember.
Thanks

[#2]

I've come across this on someones laptop before.  I found a load of malware on there which I cleaned up, and removed the proxy server settings and all was then ok.  I put the proxy setting changes down to some of the malware that the user had installed.

[#3]

pjmarsh, is this likely to be somehing the free versions of malwarebytes can handle or better to take it in to the shop?

[#4]

It was malwarebytes that I ran, and that did the job for me.

[#5]

thanks I'll give it a go.