Cut has errors first time run, but second time on its good

Any idea why the first time I run a file to cut it fails. The second pass of the cut always goes off track. If I reload material and then re-run the file it cuts fine. And it happens after I’ve unplugged my laptop and come back to cut the file again. The file is a Telecaster guitar neck. So now I run on a piece of plywood to get that out of its system.