I have a client with Win XP and there is something wierd going on. Problem is this.... In InternetExplorer, when you click on a link, the page you go to comes up normally. Then the resolution of the displayed page, not the menu bar, etc. begins to expand incrementally until it reaches some limit. It is like a zoom in. In Excel, the opposite happens. Once you edit a cell, the worksheet cells begin shrinking to a set limit. Like a zoom out.
Try another keyboard