From what I've read over the years, it seems that some people run into this all the time, and most never see it.
Of course, that doesn't help at all.
One thing about version 3.043.022 mentioned earlier. It has a serious bug that can cause Mach3 to hang on M6's, depending on the contents of the M6Start macro.
While testing when I first found it, I could get it to freeze when the M6Start had just one line of code. It definitely doesn't work with the M6Start in the 2010 Screenset.
And that there stops any thoughts of using 022 for me too - I have a fair bit in M6 and I use the 2010 screen set.
There is nothing worse than a random bug, there is no pattern to it, most of the time it will run all day then others it will fail after a few hours and others like yesterday it will fail upon first run.
I'm very limited in what software I can run due to using a CS-Labs controller.