ASP.net 2.0 Forms Authentication spordically fails.

[toptomato]

I have ASP.net 2.0 Forms authentication enabled:
My web config settings are:
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<authentication mode="Forms">
<forms loginUrl="~/SSLPublic/Login.aspx"
protection="All"
timeout="30"
path="/"
requireSSL="false"
slidingExpiration="true"
defaultUrl="~/Secure/Inventory.aspx"
cookieless="AutoDetect" />
</authentication>
<membership>
<providers>
<remove name="AspNetSqlMembershipProvider"/>
<add connectionStringName="DBConnectionString"
enablePasswordRetrieval="false"
enablePasswordReset="true"
requiresQuestionAndAnswer="false"
applicationName="WebManagement"
requiresUniqueEmail="true"
passwordFormat="Hashed"
maxInvalidPasswordAttempts="5"
minRequiredPasswordLength="5"
minRequiredNonalphanumericCharacters="1"
passwordAttemptWindow="10"
passwordStrengthRegularExpression=""
name="AspNetSqlMembershipProvider"
type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
</providers>
</membership>
<roleManager enabled="true">
<providers>
<remove name="AspNetSqlRoleProvider"/>
<add connectionStringName="DBConnectionString"
applicationName="WebManagement"
name="AspNetSqlRoleProvider"
type="System.Web.Security.SqlRoleProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
</providers>
</roleManager>
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Everything was fine for almost 4 days and then all of the sudden i was unable to login. I started recieveing following error message logged in the event log:
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Event Type: Information
Event Source: ASP.NET 2.0.50727.0
Event Category: Web Event
Event ID: 1315
Date: 6/3/2006
Time: 1:10:18 AM
User: N/A
Computer: PROTOTYPE
Description:
Event code: 4006
Event message: Membership credential verification failed.
Event time: 03/06/2006 1:10:18 AM
Event time (UTC): 03/06/2006 5:10:18 AM
Event ID: 5254f20d384a4419bb209ae99c5d287e
Event sequence: 3
Event occurrence: 1
Event detail code: 0

Application information:
Application domain: /LM/W3SVC/153682931/Root-3-127937849878125000
Trust level: Full
Application Virtual Path: /
Application Path: C:\Inetpub\

http://wwwroot\p1\EnterpriseManager\

Machine name: PROTOTYPE

Process information:
Process ID: 4056
Process name: w3wp.exe
Account name: NT AUTHORITY\NETWORK SERVICE

Request information:
Request URL:

http://www.mywebsite.com:10011/SSLPublic/Login.aspx

Request path: /SSLPublic/Login.aspx
User host address: 64.229.145.247
User:
Is authenticated: False
Authentication Type:
Thread account name: NT AUTHORITY\NETWORK SERVICE

Name to authenticate: storeadmin

Custom event details:

For more information, see Help and Support Center at

http://go.microsoft.com/fwlink/events.asp.

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I deleted the database and recreated the database from backup and it started working fine again. However every now and then it fails again with the same error message logged in the event log. Really troubling, any ideas.