Jumping Letters

My letters keep jumping to another part of the page when I am typing, so suddenly I notice that I am typing in the middle of another sentence.
It has happened with Word, Excel and an HTML software I use.
Why does this happen and what can I do about it?

 

Sounds like you need a new computer, J/K I really don't know, never happened to me.

 

also happens to me at times... here in my laptop. But not in my desktop pc...

 

Your computer could be suffering from momentary lag or it could be your touch pad if you have a mouse.

 

A momentary lag would not make it jump back into the middle of another sentence. I am using a laptop and do not use my touch pad when I am typing, just my keyboard.
Could it be a virus or a bug?

 

I notice that occassionaly but it normally occurs when someone send me an IM which in turn is opening a new window.

 

This happens to me all the time, online or offline. With Microsoft office and other programs too. Any suggestions?
Could it be a virus?