Re: Burn Bootloader to ATmega328P-PU on a breadboard
What programmer did you select? When you selected the USBtiny device, it will look for a USB port.
But when you select the 'Arduino as ISP' option, it will start looking for a COM port.
So double check what programmer you have selected in the Arduino software.
(When using avrdude to flash the IC manually, just give avrdude the right port using the -P parameter. (Capitol P !))