I own a 20" dell

most likely capacitor problem as these caps only have a 25000-40000 hour life span. when you do replaace the monitor , turn it off when not at the computer. even though it goes into sleep mode there is still a current running through the unit cuz if you move the mouse or hit button on keyboard display wakes up. I know this because I have done boad level repair on panels

Have you unplugged the power cord to the LCD? Let it sit for a minute, then try it. ALWAYS buy a UPS and plug any computer devices into it. Doesn't have to be big, a $50 unit will protect it from dangerous voltage surges.

Connect a different monitor to your computer, if it still displays the same fault the the problem is the video card and you need a replacement.

your monitor got a hardware problem:
1) the LVDS controler board out of work, only change or repair it could be fixed.
2) if you can see some show like smaller signal detect windows in the centre of screen a very short time (bright flashing one time), this is inverter board damaged or worn lamps, thay all need repair or replace
hope give you some idea. please take a rating let me know how much helped you thanks!

replace the monitor: it's lost vertical scanning

If you have another computer, try hooking to it and see if it flickers on it too.
If you hit Ctl-Alt-Delete and choose Task Manager, does the box flicker there?.
Adjust the monitor ratio in the Display Settings/Display/ Display Adapter Properties, Monitor Tab, see drop down (increase screen refresh ratio to higher number).

This may be caused by the death of a display driver circuit and these might be integrated with the display itself. 
The pixels on the screen are controlled by an X-Y matrix and the matrix may have signal lines that are somewhat shared for different screen positions.
I doubt that this is DIY project and the failure can only be located by an equipped and trained tech. 

please refer to this link for help..
http://support.dell.com/support/edocs/monitors/2001fp/EN/trouble.htm

Hello Lunhoo,
Your TV should still be in warranty. If so, yes you should take it in for repair. Even if it's not in Warranty, Akai may have a special warranty extension for your TV. Check it out.
Good luck.

I had the same problem with my monitor, saw only coloured vertical lines. I opened it, opened the back of the metal casing to get access to the circuits. There I found a loose connector. I reset it and it worked again!