Issue with cable stability?

Hey guys, a couple of weeks ago I noticed my cable internet stability flucuating. Sometimes it would run fine for days… other times it was minutes between disconnects.

Talked to my ISP and they tried to help each time saying… well you look connected from our end, only to have it work momentarily and then disconnect during a game like BF2. They have a tech rolling out in a few days to test the signal.

My question is… would there be anything from my TCP/IP or network etc that would cause my modem to constantly reset? or is it most likely a signal?

I noticed it when I started playing BF2 and BF2142, are those a possible causes for some strange reason or just a obvious means of detection?

(modem is a linksys, cpu= dell XPS 600, 2g RAM, NO router)

P.S. cat chewed the power supply cord to modem and severed the circuit, replaced it with a power supply from my old modem. could that have fried the modem?

THX ALL