DeliveryInDoubt error when Spring Security concurrency control is on

Hello,

I have strange problem and as far as I know it is somehow connected to Spring Security. My application uses Spring 3.0.5, Spring Security 3.0.5 and Spring Flex 1.5.0 (client-side is written in Flex). Basically when my application is deployed on a server and accessed via internet it responds randomly with this error:

Quote:

---

Client.Error.DeliveryInDoubt
Channel disconnected before an acknowledgement was received
Channel disconnected
null

---

For example I log into the app nad pick some function which sends request to a server. Then I get this error in respond. Second call to the function occurs with no error - everything is fine. This is weird. When running local my app works just perfect.

What I have discovered so far: I wanted to prevent users from logging in more than once. Thus I have this tag in my application.context:

Code:

---

<security:http entry-point-ref="preAuthenticatedEntryPoint">
<!--                <security:anonymous enabled="false"/>-->
                <security:session-management>
                        <security:concurrency-control max-sessions="1" error-if-maximum-exceeded="true"/>
                </security:session-management>
</security:http>

---

When I removed it, everything started to work. No mentioned error.

Some information about server and library configuration:

CentOS release 6.2
2.6.32-220.7.1.el6.x86_64
Tomcat6 6.0.24 35.el6
jre-1.6.0-sun.x86_64

Spring 3.0.5
Spring Security 3.0.5 (also tested with 3.1, no difference)
Spring Flex 1.5.0
BlazeDS - I'm not sure which number, but probably 4.0.1.17657