Monitor screen moves up and down automatically. It is new monitor purchased six months back. Problem was experienced in the old monitor

Have you tried changing the Screen Refresh Rate higher?

I have XP and get there by:
Start
Control Panel
Display
Settings
Advanced
Monitor
See if there is an option to change it higher than the default 60.
You might need to change your screen resolution before changing the refresh rate because not every screen resolution is compatible with every refresh rate. The higher the resolution, the higher your refresh rate should be.