What OS are you using, Windows ??
You mentioned your MSI board, and now you have the ASRock. Are you using the same Windows installation from the MSI board?
I'm not sure I understand, your mouse and keyboard are PS2, and you're using a PS2 to USB adapter, and that does not work? On all of the USB ports?
Have you tried, in the Advanced -> USB Configuration screen, to disable Legacy USB Support. Sounds wrong, I know, ASRock suggests that in some cases.