This topic actually belongs in the altcoin mining subforum.
That being said, your initial description of the problem isn't really informative:
--snip-- my cmd mining frezzes after 3 days :/ --snip--
Could you at least tell me/us:
- Which mining software you're using (you already told us you're mining ravencoin)
- Which distro you're running and how you set everything up
- If there are error messages being shown
- If there's anything in the syslog/debug log
- Wether or not you were running in daemon mode, or maybe using screen over an ssh connection... Or were you working straight from the console.
- Did you OS freeze, or just the miner
- Which steps you already took in order to debug the problem
- Maybe even some profit calculations... I don't know if it's worth a lot of time to investigate if you estimate to make a couple cents a year vs several thousand $?