[bndb]

First of all I would like to thank bbeard67 for answering my query. However answer to the specific query of bbeard67 are as follows:

Though the problem started with a game only, later I found that it parmanently affected the 640 x 480 mode of display. All the games run with 640 x 480 mode. Hence after the problem started, whenever a game is run, the screen turns upside down. First I thought it is the problem with DirectX driver. But later when I changed the display setting to 640 x 480 mode manually, immediately the screen turned upside down. Again if you change to any other mode e.g. 800 x 600 or 1024 x 768, the problem vanishes.

I deinstalled the display adapter and then re-installed intel extreme gaphics. But the problem persists. Is it possible that a startup program while booting changing the settings for this mode? Can any one throw some light to sort out this problem?