Although you have increased the "Maximum Log Size" in Event Viewer from the
default of 512 KB to a very high value, the corresponding event log file
does not grow beyond a certain size.
With Event Viewer, you can specify a maximum log size of 4 GB separately
for every log (System, Security, and Application). In the current design of
the event log facility, the combined size of all log files does not grow over
approximately 300 MB, depending on the memory situation. If the log is
configured to "Do not overwrite events," new events will not be written.
Avoid setting the event log this high. Depending on the amount of events,
back up and clear the event log on a regular basis, and configure the log
to "Overwrite Events as Needed."
To back up the log, you can use Windows NT Backup, or DUMPEL from the
Windows NT Resource Kit.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.