Samsung phone repeatedly mounting, and unmounting.

I have a samsung galaxy s3 plugged into a front usb slot on my cyberpower pc, running windows 8. For charging.
My previous computer never had any issues but this one (which is brand new) is having a lot of annoying problems with it.

It has no issue detecting the phone, but any time I touch the phone while it's plugged in. The computer will repeatedly (7-10 times) play the dismounting hardware sound. Followed by several mounting sounds. Over and over for a little while.

I thought maybe it was a connection problem with the cord. But it happens without any interference with the cord. All I have to do is press any button on the phone once and it will mount and unmount the phone obsessively. Which will also open and close the folder for the phone's files, interrupting everything I'm doing at the time.

Did you try the back USB ports? There could be a problem with the front USB ports, another thing you could try that worked with my note 3 (I was having a similar problem) is see if usb debugging is enabled in Settings > Developer Settings on the phone, if so disable it.