Why does my computer keep disconnecting from the internet under times of stress?

[kittyman1995]

It seems my computer disconnects from the internet when ever I get bad lag in a game. Like, I'll be playing along and I'll get a really bad lag spike and it will just be like "Okay, I'm done." and disconnect. Restarting the computer fixes the problem, but doing that is a pain because 1/3 of the time that "DSKCHK" (Or whatever) thing comes up claiming that my "volume is dirty" and then proceeds to take a half hour to fix it (Has 3 parts), and then it takes another 20 minutes to log onto my account (Me and my parents share the computer). I can go into the control panel and it says that the modem is disabled and it won't let me re-enable it. I was wondering if there is a some way to remedy this because it is starting to anger me.
And this is a wired connection to a desktop computer directly from the modem, no routers involved.