You have a laptop, don't you? This is a very common issue for people who get a laptop for the first time... Sometimes even long time laptop users. The problem is you're resting your palm(s) on the trackpad which is being interpreted as a tap-click gesture.
MOST, though not all, trackpad drivers have some kind of option you can set that tries to eliminate this. It's not fool proof, but it will usually cut the occurrence rate of the issue down significantly. You'll have to go exploring on your own, since this option (if it exists) is stored in a bunch of different places depending on what trackpad your laptop has. You also neglected to mention any kind of specifics about your system in the event someone was kind enough to go google instructions for you.
When typing message cursor jumps backwards and seems the margins are not set correctly. It has been doing this about 2 months. Can anyone explain how to fix this problem?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic