Mach 3 ( R3.043.066) is tripping the e-stop. This has happened before and I was advised to check the connections because it was caused by a drop in power.
Could there be any other reasons?
I have RESET and pushed PLAY and it may continue at the same line or it may move to another line of g-code and ruin my work!

Hi,
don't know what to make of the Estop triggering like that, electrical noise maybe?.

Once the machine Estops it has by definition lost Reference and you cannot just restart the machine and expect it to pick up where you left off.
You should re-Home your machine and either start the job again or use Run-From-Here (RFH). Note if you use RFH you will have to experiment
with it quite a bit so you are absolutely familiar with the procedure or you will crash. RFH has caused more crashes in Mach3 than all other sources.

Craig