Philips 17 inch 170s4fg lcd monitor,display flickering

Yes, have your videocard put out a signal the monitor tolerates better; the vsync might be off (52Hz or 70Hz. or something) what it can cope with well. Just read through the manual's specsheet and the monitor status screen together to see if they sync. It might be in graphics card advanced settings, it might be the XOrg configuration....

If the monitor is connected to a DVI output on your computer try to connect it to the VGA to see if it's an issue with the input or if the monitor is shot. It sounds like your monitor just crapped out.

Check that the Video cable (VGA or DVI) is not damaged, if you move it does the screen go on and off?

If not then the circuit board inside the screen is faulty and needs reparing

The lock/unlock function is for locking out the control buttons on the monitor.
http://www.fixya.com/support/r4646147-philips_lcd_monitor_loc_unlock

Try this: http://www.fixya.com/support/r4646147-philips_lcd_monitor_loc_unlock

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

More likely to have capacitors failure in the power supply, that will be the first thing to kook for inside, it can also be failure in the backlight inverter circuits, lamps. see example of failed monitors due to bad caps: http://s807.photobucket.com/home/budm/allalbums

Sounds like you may have a bad video cale or a dmaged or bentpin in the connector, remove the cable from the monitor and look at the pins on the connector

I believe this is the end of your monitor. Maybe it bit the dust by the time you read this.

Sounds like your OSD is locked. Press and hold the "OK" button for 10 seconds or so and it should unlock.

Check VGA Cable