The error message you refer to is can be caused by many things however the 2 most common I see are:
1.Faulty memory - I see they replaced this on the first machine
2. Overheating inside the case sometimes from the GFX and a lack of airflow inside the case.
If it was 2 then would expect Mesh to have a lot of calls on this.
My money would be on 1. the RAM.