hi, pls help me. i have this PROBLEM yesterday. i just left my computer on standby mode to have lunch and when i return to do my work, my monitor remains blank, then i restart my computer. and the same problem occurs. i've try totest my monitor and its working good. then i try to test my computer to other monitor, and still the same problem occurs..I may be on the wrong track but ....   Is this in an office setting, where other people also work?  Could someone else have been tampering with your computer while you were away?

Did you have your computer set so that you needed to LOG on, i.e. enter a password, when it came out of Standby? 
YES im in a office, but no one can use my computer because i always lock my room.When you start the computer, nothing is on the screen, even booting sequence?nothing apear on the screen only the SELF check of the monitorreinsert your RAM and CMOS BATTERY... i already try it but nothing happen still d same Do you normally see a light flickering on front of your computer when you startup, that light representing hard drive activity?  How about now, do you see the usual indication of hard drive activity during startup? 

Can you access the BIOS and see whether it's recognizing a hard drive?when i push the power botton, GREEN and red light appears, but after few seconds only the green led remains on. i replace my harddisk with another,  i also try to replace my video card, and memory card, but same problem occurs,Start over by clicking here...