ASP.NET deadlock

we are using ASP.NET 1.1.4 and we are getting event id logged once a day;

Event Type: Error
Event Source: ASP.NET 1.1.4322.0
Event Category: None
Event ID: 1003
Date: 6/27/2007
Time: 3:28:58 PM
User: N/A
Description:
aspnet_wp.exe (PID: 6544) was recycled because it was suspected to be in a deadlocked state. It did not send any responses for pending requests in the last 180 seconds. This timeout may be adjusted using the <processModel responseDeadlockInterval> setting in machine.config.

Application was running properly and machine.config havn't change for a while .
what might be a reason for sudden deadlocks ? and how we can identify what's causing it?
Thank u!

viktoria