This would suggest loss of control after inadvertantly entering IMC.
Sigh
Even if it's just speculation, this is such a terrible thing and could be avoided by requiring a little bit of IMC training for a PPL. Most PPL instructors don't have an IR and you get told how terrible IMC is, how little chance you stand as a PPL, etc. I never dared getting even close to clouds and was in total awe when I started my IR. Turned out it's not a big deal at all, stay calm, look at your instruments.
IMC training and IR rated FIs should be mandatory for every PPL. Unusual attitudes under the hood should be equally mandatory.