If it's the same guy, I'd be sceptical of him reinstalling a genuine copy of Windows if the original version he installed is cracked. Honestly though, you should be moving to Windows 10 regardless as Windows 7 is no longer supported.
My best advice would be to perform a genuine Windows 10 installation and see how the PC performs. I suspect the root cause of the issue is faulty RAM, but cracks (especially old cracks like Orbit30) can cause weird behaviour.
Per forum rules, we cannot assist with illegal copies of Windows, but we can assist you reinstalling a genuine version if you need help with that.