Oh sorry, forgot to mention the software.
The rendering problem appears on Sony Vegas 13.
I'm using an older ASUS a53s laptop, with upgraded memory:
Windows 10 64-bit
Intel Core i7-2670QM 2,20Ghz 4 Cores
8GB DDR3 Ram
440GB HDD
Nvidia GeForce 610m
If there's anything else you need to know, tell me right away.