event log full message on t310 widows server std 2008 r2

We have set the log files to overwrite yet no matter what we do the led on the server itself displays a message that the event viewer is full and the server is barely functional and have to reboot.  we even tried changing the settings in registry as well to no avail.  This is for a CPA firm here at the march 15 Corporate deadline and they are having to reboot at least every morning and even later at times as well.  Thanks in advance for any help on this issue.  Burr