The level of messages logged can be controlled by giving different severity level.
When you select a severity level, the device logs all syslog messages of that level and above. For example, if you select critical, the switch logs error messages for critical, alerts, and emergencies.
The default severity level to log is errors.
In all cases, the severity level defines the amount of detail to be logged
The follwing are the severity levels and the description:
1)emergencies :The switch is at risk of failing.
2)alerts: A condition exists that should be immediately corrected.
3)critical: A critical condition exists, such as a hard device error.
4)errors: Error messages.
5)warnings: Warning messages.
6)notifications: Conditions that are not errors but could require special handling.
7)informational: Informational messages.
8)debugging: Messages only used for debugging.
Try changing the level of your logging and see if it works
Here's the document for the same:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/7_4/config/logging.htm