Event Id 5401

This issue is related to permissions. You can easily fix it by granting full control to the LOGS folder listed below for the WSS_ADMIN_WPG group, and Read & Execute to WSS_WPG group.

You may be getting this error because of KB948496

Event Type: Error
Event Source: Windows SharePoint Services 3
Event Category: Unified Logging Service
Event ID: 5401
Date:  3/18/2008
Time:  11:10:20 PM
User:  N/A
Computer: xxxx
Description:
Tracing Service failed to create the trace log file at 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\LOGS\'.  Error 5: Access is denied.