I've set 'hardstatus alwayslastline "%H: %n %t | %w | %l | %c:%s"' in my .screenrc. The clock in the status line stops if the system time is set to an earlier time, e.g. via ntpdate: # ntpdate time1.ethz.ch 13 Aug 10:57:58 ntpdate[8848]: step time server 192.33.96.101 offset -2999.553470 sec # Detaching and reattaching solves the issue. See for http://bugs.debian.org/674907 for the reason of such time shifts.