Atmega8u USB converter malfunction

Recently my arduino uno clone began generating error messages on connection to pc, specifically "One of the USB devices attached to your computer has malfunctioned." The arduino was able to run the last sketch. Drivers have been reinstalled, different computers and operating systems used but to no avail.

I believe the Atmega8u is able to be reflashed using an AVRISP or similar. Since it is not able to communicate over USB, I must find some alternate way to reprogram it. It is of course possible that the arduino is beyond repair, but I think it's worth a try. I have an arduino mega 2560 which I would like to attempt to use as ISP to program the Atmega8u with the default firmware. I have tried using atmel's flip to program, but I cannot get the drivers to install for the mega, which gives errors.

I attempted to follow this http://blog.ethanfrei.com/2011/10/arduino-uno-revived.html but was not able to, as I was unable to locate avrdude. Also, I attempted to follow this http://forum.arduino.cc/index.php/topic,111.0.html.
I have added a resistor to attempt to enter DFU, but have had no success.

Can I use an Arduino Mega to program my Arduino UNO's Atmega8u?
Can I use avrdude to use Mega-ISP?
Where is avrdude? (I attempted an install, though was not able to find any documentation on how to use, like actually where the executable was, or otherwise how to open it in cmd)

Are there any other solutions to reflashimg the Atmega8?

Thanks,