Hardware:
Toshiba Satellite C650D-ST5N01
AMD E-450 processor
8GB RAM

OS:
Linux Mint 15 KDE, 64bit

Problem:
When I plug in the ethernet cable, after a couple of minutes, my computer freezes and sometimes the display spazzes out (pixelates--though that is not the correct term, it's the only one I can think of which best describes the issue). Upon reboot the symptoms are repeated.

When connected via Wifi all works perfectly.

Things I have tried (but to no avail):
1. Tried installing different set of RAM (no change in behavior)
2. Tried another, similarly set up computer, with same router/modem and cable (this alternate computer works fine--does not display behavior in question)
3. Tried with a couple of different Live USBs--different distros and the 32bit version of Mint 15 KDE (no change in behavior)
4. Checked settings in BIOS and Network Manager (all seem fine; no change in behavior)

Does anyone have any input, suggestions, ideas as to how to remedy this?

Thank you in advance.

If you have the system at a virtual terminal, is a kernel backtrace printed out? The behaviour you report indicates the kernel driver for the ethernet card is likely falling over.