Dot in the center of my lcd modnitor

Hello there.

Try the monitor with ANOTHER computer,

This will prove whether it is the Monitor at fault or not.

You may have failed back light inverter board, or worst, bad lamp.
Inverter: http://www.google.com/products?rlz=1T4GGIH_enUS282US283&q=emachine+d620+inverter&um=1&ie=UTF-8&ei=-3HrS-buFIb-sgOf06nBDw&sa=X&oi=product_result_group&ct=title&resnum=3&ved=0CC4QrQQwAg

www.insidemylaptop.com
http://s807.photobucket.com/home/budm/allalbums

Please go to the repair center and chk for picture tube

I hate to say it, but that's fatal

The black dot will just grow until the rest of the screen fades.

It is pixels dieing in the monitor

i seem like your memory ic is wrong maybe the lcd or try to change your grapic card just borrow from somebody and try first ok

If the monitor does not have a symbol (similar to the letter 'C' with a dot in the middle), the cheapest digital multimeter can be used on the 'diode' or 'continuity' setting to check the input.
If the meter reads between 600 and 900, you are measuring the forward voltage drop of a protective diode.  Any other reading will mean that the positive probe of the meter is on the positive part of the connector.     i.e. If you are placing the positive meter lead on the center pin and the negative on the shell and it reads 600-900, then the power supply needs to have the negative applied to the center pin and the positive on the shell. If the negative lead is held on the center pin and the positive on the shell and the reading is 600-900 then the center pin is the positive input and the shell the negative.
The readings shown above mean that you are measuring the forward voltage drop of a diode meant to protect the unit against improper polarization and it will probably either die or ruin the adaptor if misapplying the polarity.
You can buy such a meter at electronics or auto parts stores for under $20 US.

Does the rest of the picture come in okay? Just 4 small dots? Those are probably dead pixels. I believe you have to have 5 (in most cases) to claim it as defective. Some people have had success tapping on them (be gentle) otherwise, you can send it into a repair company.

First, have you degaussed the unit to stop any magnetic interference?

Do you use software to change monitor settings or do you use the on screen display menu on the monitor?

Most lcd's have a button for menu on the lcd. This can be used to adjust color, contrast, brightness, degauss, as well as screen position and size.

Problem in the LCD back panel board. check the interface unit or ADC unit, also check the video clock pulse. one section is not working.....

Take new vga graphic card which can be use in agp slot and upgrade ur system with it. ok bye bye