This program:
---------------------------------------------------
public class uu {
    public static void main(String[] args) throws Throwable {
	long t0 = System.currentTimeMillis();
	java.util.concurrent.TimeUnit.MILLISECONDS.sleep(3);
	System.out.println(System.currentTimeMillis()-t0);
    }
}
---------------------------------------------------
should print a number no less than 3, but on windows-amd64
and more rarely, windows-i586, it often prints 0.
Probably a hotspot bug (but it could conceivably be core libraries)

This causes j2se regtest test/java/util/concurrent/TimeUnit/Basic.java to fail
Doug Lea asked,

What happens if you instead just call Thread.sleep(3)?

Good question.

-----------------------------------------------------
public class uu {
    public static void main(String[] args) throws Throwable {
	if (args.length == 1 && args[0].equals("TimeUnit")) {
	    long t0 = System.currentTimeMillis();
	    java.util.concurrent.TimeUnit.MILLISECONDS.sleep(3);
	    System.out.println(System.currentTimeMillis()-t0);
	} else if (args.length == 1 && args[0].equals("Thread")) {
	    long t0 = System.currentTimeMillis();
	    Thread.sleep(3);
	    System.out.println(System.currentTimeMillis()-t0);
	}
    }
}
-----------------------------------------------------
The above program, when invoked with either argument "Thread" or "TimeUnit"
prints "0" on windows-amd64 most of the time.
So this is definitely not a TimeUnit bug.