Netbook Screen keeps going to Portrait

My young son has a new netbook. Running Windows Vista Home Basic.

When he plays on it he somehow accidentally makes the screen go to portrait orientation (I assume to allow book like things to be read!) Also the mouse orientation seems to be opposite its usual setting- neither normal for Landscape nor correct for portrait.

How can I make it revert to normal?

Thanks

Try CRTL-ALT-Arrow Key.

Thanks but I tried that. Did not work. I wish I knew how he keeps on doing this!

Have now opened it in Safe Mode and am going to look at Display properties.

Go back to normal mode (not safe mode). Right-click on the desktop and select properties. If there is a control panel specific to your computer model, check there. Also, what’s the model of the computer? I can look up the manual online.

Thanks, that worked- I reset it to 0 degrees and it is now correct.

There must be a short cut as my son is hitting the one to send it to portrait when he is playing a game- he must be hitting it accidentally!