Here’s one for you guys

Yesterday a new client called me and said “all my icons are on their side”
When I attended the site the windows desktop was rotated 90 degrees to the left,just as though someone had picked up the monitor and turned it on its side, moving the mouse up and down caused the cursor to move left to right, moving the mouse left to right caused the cursor to move up and down.
I have fixed this issue by restoring the system to before the problem occurred but I am concerned that whatever caused it is still present.
Does anyone know of any virus or rogue software that is causing this? I realise that this is a feature of Tablet PC but this is a PC with win xp home edition installed.