desktop screen stretched out to far. why???

hello guys, i have a dell crt monitor. my model # is E773C, and i have windows xp.

 

12-25-07 my monitors desktop screen suddenly stretched out to the left and right sides, and up to the top, and down to the bottom of the screen. and i didnt do anything to make this happen. it happened on its own. for the 3 weeks before this there has been flickerings of light on my desktop screen. and it seems like words that i read on a website are moving slightly. so maybe my screen is moving, and changing shapes. so something was going wrong with my monitor's screen before 12-25-07 when it suddenly stretched outwards. and also when it stretched out, the folders on my desktop are bigger in the middle area of my desktop. and on the left and right sides of my desktop the folders are smaller. so why would this suddenly happen? is there a problem with my monitors adapter drivers?  my screen resolution has been at 800x600 since i got my monitor 4 years ago. and my refresh rate has been at 60 for the last 4 years. my screen stretched out when these 2 settings were at 60 and 800x600. if i change my refresh rate to 70 or higher, the desktop screen is Not stretched out, and the folders are the same size (a good size) but it hurts my eyes to look at the screen. and if i change my screen resolution to 1024x768 my screen is not stretched out, and the folders are the same size (a good size) but the folders are all too small. so i need the screen resolution to stay at 800x600, and i need the refresh rate to stay at 60. but why would my screen stretch out suddenly? is there a problem with my monitors adapter driver? is my monitor just broken? do i need to buy a new monitor?

 

please help. thanks.

scott