Magreet:
I checked the Arduino boards and thought they would all use external crystals. The LilyPad got one too?
All but the ATmega168 version, yes (which means the '328 version uses an external crystal/resonator).
I didn't mean to muddy the waters here, I was just trying to point out that if you want to burn a bootloader for an ATmega168 to run at 8MHz (with the internal oscillator) don't pick the pro mini but select the "LilyPad Arduino w/ ATmega168" (then "Burn Bootloader" from the menu). That will work on a stock install, out of the box so to speak.
If it's not a software problem as westfw suggests, perhaps it's time to post a picture of your setup?
Regards,
Brad.
KF7FER