IE or Firefox pages are seen not stable, if I drag it with the mouse to a particular position the screen do not remain there .The page on the screen is not stable. Same is the case with word files etc. Is it due to some virus or bugs, how can i rectify it, help is solicited.

I think more information is needed. I don't understand as what is not stable and from where to where you are dragging the page. But of course the rule of thumb is to check for virus as a precaution. Than you move on to other possibilities. Like maybe your graphics card, RAM, motherboard and so forth.

The screen (I mean the page on the screen) itself is not stable, it goes up and down. As soon as you remove your finger from the mouse, the position of the page change.

Ok. Than my suggestion is to scan for virus, check the connector to the monitor, have another monitor to test and lastly test with another VGA graphics card. Hope this help.

scanned twice but no change

Have you try with other monitor or VGA card? Have check the VGA cable? Try all this and let us know what you find.