Forms authentication failed for the request. Reason: The ticket supplied has expired.

Hai friends, ISSUE IS: Forms authentication failed for the request. Reason: The ticket supplied has expired. actullay i have implemented forms authentication concept in my application as well as i am maintaining session in sqlserver mode. i never faced this problem in local server ,but in live server getting frequently. my server log (given below) ----------------------------- Event Type: Information Event Source: ASP.NET 2.0.50727.0 Event Category: Web Event Event ID: 1315 Date: 6/19/2009 Time: 8:55:46 AM User: N/A Computer: PDCWWW02 Description: Event code: 4005 Event message: Forms authentication failed for the request. Reason: The ticket supplied has expired. Event time: 6/19/2009 8:55:46 AM Event time (UTC): 6/19/2009 12:55:46 PM Event ID: ddcb2588ca844722ab97f541551a1432 Event sequence: 1177 Event occurrence: 5 Event detail code: 50202 Application information: Application domain: /LM/W3SVC/866167344/Root-1-128898 ...