Any idea why LoginControl requires users authenticate twice with FireFox but works correctly (once) with IE? I am using a custom MembershipProvider and RoleProvider, if that matters.

Authentication portion of my web.config;

<authentication mode="Forms">
      <forms
          timeout="50000000"
          protection="All"
          requireSSL="false"
          slidingExpiration="true"
          cookieless="AutoDetect"
          domain=""
          enableCrossAppRedirects="true">
        <credentials passwordFormat="SHA1" />
     </forms>        
</authentication>

Membership section;

	<membership defaultProvider="CustomMembershipProvider">
		<providers>
			<add 
    name="CustomMembershipProvider" 
    type="CustomCrateMembershipProvider" 
    connectionString="" 
    enablePasswordRetrieval="false" 
    enablePasswordReset="true" 
    requiresQuestionAndAnswer="true" 
    applicationName="/" 
    requiresUniqueEmail="true" 
    passwordFormat="Hashed" 
    maxInvalidPasswordAttempts="5" 
    minRequiredPasswordLength="5" 
    minRequiredNonalphanumericCharacters="1" 
    passwordAttemptWindow="10" 
    passwordStrengthRegularExpression=""/>
		</providers>
	</membership>
	<roleManager defaultProvider="CustomRoleProvider" enabled="true">
		<providers>
			<add name="CustomRoleProvider" type="CustomRoleProvider"/>
		</providers>
	</roleManager>

Only code behind related to login;

protected void OnLoggedIn(object sender, EventArgs e)
{
}

protected void OnLoggingOut(object sender, EventArgs e)
{
}