We have the same problem, JBoss 4.03SP1 on Windows 2003 Server using Java 5. The only thing I can pin it on is this hotfix

http://support.microsoft.com/?kbid=908531

which is all thats changed on the server. The stupid thing is that its just the one node. The other two nodes both had the hotfix applied but seem fine.

I am willing to provide more information if it will help nail this problem.

whoops, I have to retract the last part. It is happening on all the nodes.

After using a different partition name and restarting the nodes everything is back to normal. Clearly its not the hotfix.

You may want to try using both FD and FD_SOCK, as described in the last section of the wiki (http://wiki.jboss.org/wiki/Wiki.jsp?page=FDVersusFD_SOCK)

We have the same problem, JBoss 4.03SP1 on Windows 2000 Server|Linux using Java 5