We have been having the same problem that many people with this particular make/model have been experiencing:
Whenever we are in a program that you can type in (eg. Excel, Firefox, Run, etc.) characters will begin typing and deleting erratically by itself - not randomly though - it's usually '65*-:' - something along those lines - and the the laptop switches off after a few seconds. It then often takes a while to successfully turn back on again.
This is happening more and more frequently and I noticed a lot of users with the N5040 are experiencing this problem at this very moment:
This YouTube video demonstrates the problem - and look at the comments section - many people having this problem.
I am hoping that someone can help us with this problem because no one seems to have found a solution - someone mentioned they had restored to default factory settings TWICE and it hasn't solved the issue.
The laptop is still under warranty and I would like to send it off for repair but I don't want to spend money on the premium phone line while someone talks me through reverting to default factory settings when I know that isn't going to solve it.
Some help with this matter would be very much appreciated.