at times I'm working on some thing and the page I'm working moves to the right and goes away

Hello Carlos,

It sounds as though you may have 'Swipe between full-screen apps' enabled in the Trackpad pane of System Preferences. This can be accidentally triggered, and appear to move an open window off of the screen. You might try disabling this feature, or just reversing the direction to get back to the desired space.

Mac Basics: Multi-Touch gestures

http://support.apple.com/kb/HT4721

Cheers,

Allen