i was trying to program my microcontroller and had the following error on my prolific usb com port "Windows cannot determine the settings for this device. Consult the documentation that came with this device and use the Resource tab to set the configuration. (Code 34)". i tried everything but cannot get it to work. my computer is a lenovo G560 series. i cant find any documentation on how to manually change settings.

What is the OS that you are using?

Is the USB-to-Serial Adapter providing power to your circuit of just communications?

windows 7. It has a exclamation mark on the com port. it cannot flash the controller on the make command

Is it the 32-bit version of the 64-bit version of Windows 7?

I am using Windows 7 64-bit.

I do not have any problems with the Prolific USB-to-Serial Adapter.

Under Device Manager for the Prolific USB-to-Serial Adapter I am showing:

    Driver Date     2/5/2013
    Driver Version      3.4.48.272

I would "suggest" first:

    1   Disconnect the Prolific USB-to-Serial Adapter from everything  
    2   Power-off and Power-on, (not just reboot) your Computer
    3   Open the Device Manager
    4   Plug in the Prolific USB-to-Serial Adapter
    5   Does it connect and register okay?

You did not answer if the Prolific USB-to-Serial Adapter providing power to your
circuit of just communications?