ASUS S550 wont reboot after Win7 shutdown

Hi. I have a strange one here. I downgraded from Win8 to Win7 on my ASUS S550CM laptop. All drivers look OK in Device Manager but 99% of the time the laptop will not boot - nor can I get into the BIOS screen.

*Sometimes* it will let me get past the ASUS logo screen and when it does, I can load up Win7 just fine.

If I select Restart (as opposed to Shutdown), the machine reboots just fine. BUT.. if I choose Shutdown and try to cold reboot - it won't - not until it lets me out of luck.

I've emailed ASUS (waiting response) as this machine is only 5 weeks old - one week out of its box. I just wanted to put Win 7 on the machine and didn't expect to get trouble from the BIOS.

Does anybody know what could be the problem? I'm assuming that Win7 is telling it to shutdown in a certain way which is causing this BIOS related problem.

Cheers
Paul

Absolutely no external devices connected whatsoever but thanks for the suggestion.

Neither :-( tried taking all the variables out.

I don't get it .. It's booting about 1 in 4 attempts now. Don't know if it relates to how long I hold down power button when switching on or off.

I've emailed ASUS (waiting response) as this machine is only 5 weeks old - one week out of its box. I just wanted to put Win 7 on the machine and didn't expect to get trouble from the BIOS.

whs said:

So this was originally a Windows 8 PC. There might be trouble with the UEFI. Did you see this:

UEFI (Unified Extensible Firmware Interface) - Install Windows 7 with

I can try using rufus and choose the uefi and gpt option a try. I did follow some instructions using Diskpart to get around the gpt error. Thanks. I will go make myself another flashdrive..