Serial pins, and PC USB port damaged using a USB to Serial converter (PL2303HX)
Looking at the product that you linked, the USB-to-UART is highly suspect, meaning that you probably have a counterfeit PL2303 device.  Counterfeit devices usually work, but with little guarantees.

Please check out the reviews next time.  When 'works with windows 7 but not windows 8' and 'drivers no longer available' are in the first few reviews, then the device origin becomes highly suspect!

Try the same thing with something more trusted.  Adafruit is well-trusted with the community, try one of theirs.  Yes, I realize that it is $18 instead of $7, but isn't that worth your USB port, arduino, and other hardware?