Power Issue

[Flex]

OK. Well first I have to say that this site is awesome. There are some very good tips on a variety of issues. Let's see how gifted you guys are; or show me how much more I really need to learn. I'm having a problem I've never encountered before. I put systems together for friends regurlarly, so I'm not quite a novice but clearly not a unsupported expert. I recently put a system together for a friend just like my own machine. Asus P4p800 board, Raidmax Scorpio atx 420watt case, 2.4g p4, 256 ddr400, yada yada, win xp pro.
Problem is every time I shut down, suspend, standby or whatever, I can't get the pc to power up from the case power button. I have to literally play with the power reset button on the back of the case while at the same time play with the power button on the front. All the conections are fine. I've played with the APM setting (pc) couldn't find one on the OS. I've reset the cmos, I've tried different bios setting, downloaded the lates bios version from Asus, but am not having luck and reached a point of frustration. I need help. Any suggestions would be greatly appreciated.