Hate to ask such a simple question, but have you tried making sure the monitor is off from the monitor button, then when you start your pc , hit the monitor button to turn it on? If it's always on but pc is shut down, it simply may not be kicking it in right away to tell the monitor to turn on.
That is on the simple side but to be honest, not what I feel may be wrong. Do you have your pc on carpet, or the wires crossed in the back, are they too close to a power source, or speakers etc...basically anything that may cause interference?
How long has it been since you cleaned you pc? You may have dust built up inside causing you problems. Your power supply may not be kicking in either and should be checked for dust plugging the fan etc...You may also have a bad connection to the monitor port, could be dirty, getting old etc... It could also be the source you have your monitor plugged into, the outlet, what have you. I don't suggest going into any of this unless you know what you are doing obvioulsy.Something as simple as cleaning a pc out can damage the pc instead if you aren't careful. It could also be your mainboard VGA giving problems or needs update. Do you have a graphics card, (i'm guessing no). Why did you replace the old monitor? Something happen?
i had an hp pav 7867 & pav mx70 monitor, win xp pro ver 2002, sp2, 1.00 ghz, & 512mb ram. i've replace the mx70 w. a mx703 monitor. i always shut down by clicking on start > turn computer off > turn off. now when i turn the computer on the monitor does not come on, i have to shut the 7867 down then turn it on again before the ms703 will turn on. at control panel under power options power scheme is "always on"; turn off monitor is "never"; turn off hd is "never"; & system standby is "never". help, what am i missing? is the 7867 too old for the mx703?