Desktops forum: blinking monitor

I am currently on a Dell dimension 2400 PC, with windows XP home edition service pack 2 that my mom got in 2003, that came with a 15 inch LCD monitor, & integrated graphics, but the monitor has started blinking, what happens is the screen will suddenly go black & then start blinking, with a faint light in the bottom corner, I can see the screen contents between blinks. This occurs when; I have been away from the computer a while, upon start up & sometimes when I am in the middle of something. so far what I have done is jiggle/wiggle the cord that plugs into the back of the monitor, & it usually brings the monitor back but it it is taking more jiggling the cord than ever to get the screen back. The computer seems to be ok, watched the diagnostic lights at the back of the computer upon start up, all green no red. but the monitor is very irritating. Is it the cord? before I started up today, I tried unplugging the cord that plugs into the monitor & then re plugged it back in, then started up the computer, all was well for a while, there was no blinking at start up, but then after I was away from the computer for about 10 minutes, moved the mouse & it started blinking again. The monitor is a 15 inch LCD, should I get a new cord for it? will I be able to find a new cord for this monitor? it came with the PC in 2003. Do I need to get a new monitor? is the computer dying? I need some quick help as it is hard to do my work with the monitor, want to solve the problem as I cant keep wiggling the cord that plugs into the back forever.