Use the Server Config utility to change the path:
Select Start/Programs/Sybase/Server Config.
Click the Monitor Server icon from the Products box in the Configure Sybase Servers dialog box.
Click the Configure Monitor Server button in the Monitor Server box.
Select the name of the server to configure in the Existing Servers box, and click Continue.
Type the full path name to an error log file that is not on a network drive in the Configure Monitor Server dialog box.
Click Save to save the new error log setting.
Click Exit to quit Server Config.