Screensaver timer was set wrong.Now when log in it goes straight to idle mode.

check settings looks like it goes off on timer//hibernate mode ,sleep or powersaver

Its in your power settings. Access it same as when you set the screensaver, is one way. Other times go straight to power settings.

that is most likely the sleep mode on the screen saver

open with start button

control panel

display icon

adjust screen save settings for longer

and look to see what happens in power save mode for shutdown

should work well

let me know how this goes

Setting the Sleep Time reduces power consumption by turning off the fuser inside the MFC while it is idle. You can choose how long the MFC is idle (from 00 to 99 minutes) before it goes into sleep mode. The timer is automatically reset when the MFC receives a Fax or PC data or makes a copy. The factory setting is 05 minutes.
To turn Sleep Mode off press Menu/Set, 1, 6, 2. Then use the dial pad to enter the length of time the MFC is idle before it goes into sleep mode, in this case 00 so it wouldn't go to Sleep mode at all. Press Stop/Exit.

The option is under Screen saver options or there is an idle time shut off selection under Power Saver options as well. When you select your screen saver there is are specific options to customize how it shows and how long before it activates. Some screen savers have more options than others.

To set paragon timer: Pull large round dial straight out towards you, then rotate dial until correct time is lined up with stationary 'pointer' on front of dial

plz try to boot in safe mode and in norml mode, if the problem is not solved then you have to repair the operating system

Dell monitors automatically go into power-save mode after a preset amount of time when the computer is inactive. The Dell monitor will go completely black, instead of showing a screensaver. This doesn't mean that your Dell computer has shut down. Instead, this allows your monitor to essentially turn off until it's needed again. You can change how long it is before the Dell monitor goes into power-save mode by changing your display settings.

1. Step 1 Press any key on your keyboard or move your mouse. Either will turn off power-save mode. Alternately, you can press the power button on your Dell computer tower or laptop.
   
2. Step 2 Press any key a second time if the monitor goes from power-save to stand-by mode. Stand-by mode allows the screensaver to appear.
   
3. Step 3 Enter your user name and password into the login prompt if your computer requires a login. Press "Enter" to begin using your Dell computer.
   
4. Step 4 Change the display settings on your Dell monitor to prevent your monitor from going into power-save mode prematurely. Right-click anywhere on your desktop and choose "Properties." Click the "Screensaver" tab and press "Power." Beside "Turn off Monitor," choose a time amount from the drop-down list and press "Apply."
   

try doing a system restore from safe mode logging as an administrator

Black screen is probably a screen saver or the screen is turned off by power management software.
Check your screensaver setting. Change the screensaver to None to disable screensaver.
I assume you are using Windows XP.
If the LCD is turned off by power management, on the same screen with screen saver, on the lower part of the box there is a Power button. Click to open Power Options Properties. Set your monitor power properties there.
When the screen go blank and you have to push power button, probably the computer is set to go to stand by mode after some idle minutes. You can also set it here in system standby setting.
Regards, 
Dapid Candra