Hungry For Hits will log all accounts off at 3 occasions every 24 hours, at 7:05 am, 3:05 pm and 11:05 pm (server time, EST). The logouts are made every 8 hours to ensure the site is quick, fast loading, and that no old sessions are wasting energy in the background.
If you experience you are being logged out at any other time, it is most likely due to temporary internet lag. Don’t click the surf icons before all of them have loaded, and click a bit more slowly. It may also help if you clear your browser’s cache.