Auto mode, reaching first point of coord then "reading" state, no movement

Hello,
I was trying figure it out and find answer but without success.
Have You know why in auto mode and MDI sometime machine stuck in reading state without execution of program? Just simple turn off and on again LinuxCNC is helping, but it is not a solution. In machine status I didn't find any interesting thing. Every parameter look same when working normally and when stuck in reading state.
For example if first line is G01 Z5 F100, and when I manually move axis to Z10, then first line of program will be executed, and machine stuck, next line is simple G01 X1 Y1 F100. MDI commands not working then also.
Thank You in advance