|First of all try an external monitor on it to make sure it really is a screen fault. If that does it too then let us know.|
If it is the screen itself then you either repair or replace it. Sometimes screen problems can be due to the cable connecting between the computer and screen (they give trouble where it hinges back and forth). In these cases you can often see a tell tale change by watching the screen then closing it slowly until it is nearly down.
The connectors can also work loose at either end.
EDIT: I've just realised that you probably mean "adjust" the screen. If so what particular adjustment do you make that temporarily fixes it?
Always pop back and let us know the outcome - thanks
message edited by Derek