Windows does not like inaccurate time. When the system time between a domain controller and a remote machine is more than 5 minutes apart, the remote machine will not be able to authenticate, and the user at the remote machine will not be able to log on. Not the start to a great day.
Windows SharePoint is no exception. If the system time gets moved forward and then moved backward due to misconfigured or low accuracy time servers, the SharePoint Timer service becomes very unhappy. In this case, system time was moved forward roughly 24 hours, then corrected a few hours later moving the clock back 24 hours.
The SharePoint Timer Service maintains a cache folder which keeps track of what is going on. In a farm environment, individual servers can enable a "Timer Lock" which prevents other farm servers from performing jobs. The timer lock is used when critical jobs are being ran that should not be interruped or possibly conflicted with by jobs running from other servers.
When the system time gets disrupted, the result is cache files that are newer than the current time. Then the Timer Service doesn't know what's going on, starts freaking out and puts the following warning message in the application event log every 5 minutes:
SOURCE: Windows SharePoint Services 3
Event ID: 5219
Task Category: Timer
The timer lock for Web server 'servera' was overriden by Web server 'serverb' because the lock had not been refreshed within the 20 minute timeout. The timer service on 'servera' may be malfunctioning.
To correct the problem, perform the following steps on the server experiencing the timer lock issue:
The config folder will repopulate and the warning message should stop appearing in the application log. If ALL SharePoint servers are exhibiting this behavior, perform the above steps on each server and wait at least 5 minutes between servers.