I have been trying to isolate a problem with mach3 on my system.  I have had mach3 lock up and display the error send to MS message and then mach3 will close, but appears to leave the engine running.  I then shut down my machine and it does not completely shutdown and I have to turn off the power to the system.  Mach2 works fine.  It seems to have something to do with G54, but I have not been able to isolate the problem  What I have narrowed it down to is if I run a program with G54 in it the system will hang on that line.  If the system hangs, it will continue to hang on multiple restarts, but if I use the conversational wizard and do a simple cut circle program and run it then I am able to run the file with no problems.  If I try and run the file first, then Mach3 locks up. Attached is the first few lines and it is the last line that the system locks on.  I tried to attach the file but it is to large.
Any suggestions?
 
% ( MYAPP01 )
O1
G20
G00 G17 G40 G49 G80 G90
( TOOL COMMENT IS NOT FOUND )
T1 M06
G00 G90 G54 X1.7839 Y1.6194 S7487 M03

I just tested your file and it ran here... But I would take out the % and the O1

You are only going to need to have a program number if you are calling it is a sub in the same code. As for the % you just don't need this... You look like you are a Fanuc guy

Hope that helps
Brian