I plugged in this monitor to my PC but have a box dead center in the middle of my screen that says..."Signal out of range". Anyone have any ideas why this might happen?

Look for the power button/switch on the monitor

you may try this came from manual.
Power Management" "countdown 20 sec
INPUT SIGNAL OUT OF RANGE
This OSD may appear to inform you that the signal being sent to the display is not within its frequency range. In this case, you would need to check the resolution and refresh rate you have your video card set to, and adjust to be within the range of the display

usually points to the resolution settings of the graphics card not matching the monitor resolution settings. Reboot to safe mode on the computer and set the resolution to a lower one. A good starting point would be 1280 x 960 at high res. See if that works

Out of range typically means that the resolution in windows is set higher then the monitor can support. You will need to get into windows to remedy this.
You can do this one of two ways. You can try to hook up to a more advanced monitor and do it.
OR
If you have video at first, you can press F8 as the computer is starting to boot up. this will open the advanced booting options menu. Select Run in VGA mode OR you can try Safe mode. Once you are in there you can change the resolution by Right clicking on the desktop and selecting Properties or Personalize. Then under display settings you can adjust the screen resolution using the slider bar. Set it to something like 1024x768 and then save exit and reboot normally. Once in there you can look up the max screen resolution your monitor supports and set it accordingly.
Hope this helps. Please vote if so.

that means your monitor is working fine, just check your video connection on both ends of the monitor and PC.

maybe your PC has two video cards, try to plug in another video connector

It is telling you that the PC video resolution is too high for this monitor, unless there is problem inside, you should set the resolution to the native resolution of the monitor.

http://www.fixya.com/support/r4873371-fixing_out_range_format_not_supported

Please leave rating if it helps.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague
Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.

It shows out of range because the PC is sending out the video signal that is higher than the monitor can display, you need to set the PC video resolution to the native resolution: 1024 x 768 @60Hz. You can reboot the PC into save mode (hitting F8 key while booting up) then set the resolution to 640 x 480 (try 1024 x 768 if it allows you to do so), reboot and reset the resoltion to 1024 x 768 @60Hz.

the monitor is not properly connected to the back of the PC box, check the cable that goes from the monitor to the PC box, (first unplug the PC/monitors from the power socket)
check if the cable is loose from the monitor jack point on the back of the PC box, remove it and blow air in it may be some dust is there.
fix it back and tighten the two screwes with a screw driver.
power it back ON

REMOVED THE 15 PIN PLUG - I GET A SCREEN MESSAGE - SYSTEM CABLE DISCONNECT! WHEN I PLUG IT BACK IN THE MESSAGE RGB NO INPUT SIGNAL APPEARS FOR A FEW SECONDS THEN THE MONITOR GOES INTO STANDBY AND THE SCREEN STAYS BLANK,

I ALSO PLUGGED THE MONITOR INTO MY LAPTOP AND THE SAME MESSAGE APPEARED

input signal out of range would normally indicate the the screen resoloution is either too high or too low for the monitor to display properly.

is this on just one game? which version of windows do you use?