This is most commonly caused by one of the computer (or printer) being set to a static ip address. You can check the status - by typing 'view network' in the start button search box - and selecting 'view network connections' under the control panel
you should see a couple connections - something along the lines of 'wireless connection' (if the other computer is wired it would be wired connection) - right click on that and select properties - scroll down the list until you see 'internet protocol version 4' and double click on that. - These should be set to Obtain Ip Automatically - If not write down the numbers (all of them) and change settings to Obtain Automatically. See what happens. If you completely lose internet connection even after a restart go back and put numbers back in.
you probably don't have to check the printer but if you do almost every printer menu is different I would want manufacturer and model if I try and lead you through that.
This can also be caused by a router going bad - how old is your current router?
Edited by AngryRaisin, 27 February 2013 - 06:55 PM.