Quote Originally Posted by charlieuk View Post
via loading g code through a memory stick.
Just to clarify, are you running code from the memory stick, or copying it to the PC before running?
I have heard of a few times where running from memory stick/external drives that has caused problems.
There are settings where USB will go into a low energy/power saving mode after a set time of inactivity, and if it does, it takes a little bit longer for Mach to read the next chunk of code, which can cause it to stall briefly. Copying the file to PC should eliminate that issue though.

Also, as Jazz mentions, ensure all the power settings are set so the PC is always on. On modern PCs, you usually have to create a new power plan with everything set to always on (Control Panel -> Power Options)