FULL PRODUCT VERSION :
Test case exhibits bug on:
Linux dt-000839 2.6.35-30-generic #56-Ubuntu SMP Mon Jul 11 20:01:08 UTC 2011 x86_64 GNU/Linux
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) 64-Bit Server VM (build 21.0-b17, mixed mode)

and

Linux wilf 2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:02:55 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
OpenJDK Runtime Environment (IcedTea6 1.10.2) (6b22-1.10.2-0ubuntu1~11.04.1)
OpenJDK 64-Bit Server VM (build 20.0-b11, mixed mode)

Test case does *not* exhibit bug on:
Linux wilf 2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:02:55 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
See comments in Runtime version


A DESCRIPTION OF THE PROBLEM :
A Runnable submitted to a ScheduledExecutorService having a core pool size of zero is never executed.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached test case

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
"Hello" is printed to stdout
ACTUAL -
The Runnable is never executed

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

class ScheduledExecutorTest {
    public static void main(String[] args) throws InterruptedException {
        final ScheduledExecutorService ex = Executors.newScheduledThreadPool(0);
        ex.schedule(new Runnable() {
            @Override
            public void run() {
                System.out.println("hello");
            }
        }, 1, TimeUnit.SECONDS);

        ex.shutdown();
        ex.awaitTermination(5, TimeUnit.SECONDS);
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Increase the corePoolSize to a value greater than zero.