I think this is it and why it got enabled when I updated to build 403 I don't know (and didn't appreciate as I first thought I was doing something differently).
it still forces you to set a minimum of at least "1" as the value.
The '1' value = 1 millisecond (ms). One second = 1,000 milliseconds. One millisecond is 1/40th of a frame in 25 fps; 1/33.33rd of a frame in 30 fps. If setting to 1 ms causes a problem, then there's likely something else that is not working as it should.