Miner going offline periodically for some reason?

I just started mining RavenCoin yesterday, very excited. First coin I've ever mined before. I don't have a "rig" it's just my personal computer with a paltry 6Mh/s. I am using NB miners program with 2miners pool, and I have an alert setup with 2miners to notify me when my miner goes offline for more than 20 minutes. And I get multiple notifications a day. My computer sits at home all day unused, it doesn't sleep, hibernate, or log out. I did all the stuff on Windows to make sure it doesn't. The only thing running on my pc is the miner and my Raven Wallet.

Is this normal? Or is it because my card is so weak it just stops sometimes? I already mine so little I don't wanna lose any time mining if I can help it.