UnsupportedOperationException, UnregisteredAgent

I am getting the following exception... with build 5504. (never happened 5433)

This thing is intermittent...
I have encountered this twice today...( i installed 5504 yesterday..)

what am i missing

I am using starteam as the vcs...

Any ideas...??

thanks

*************************
: Checking for changes

: java.lang.UnsupportedOperationException: Not implemented in jetbrains.buildServer.serverSide.impl.UnregisteredAgent
java.lang.UnsupportedOperationException: Not implemented in jetbrains.buildServer.serverSide.impl.UnregisteredAgent
at
jetbrains.buildServer.serverSide.impl.UnregisteredAgent.run(UnregisteredAgen
t.java:12)
at
jetbrains.buildServer.serverSide.impl.BuildStarter$1.run(BuildStarter.java:3
0)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown
Source)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown
Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown
Source)
at java.lang.Thread.run(Unknown Source)
: Build finished