Miky, I remember (while looking at Mach3 videos on Youtube) something relating to Soft Limits exceeded making Mach3 crash (blue screen of death) unless you (????) within a certain (short) period of time. I wish I could remember what the ???? was that you are supposed to do. So this may not be attributable to the driver. If I come across that again, I'll post it here.
PS: Just got my motor drivers in the mail.