Thanks for the reply. The situation you showed happened to me too. I left my truck on a hill next to a moutain to climb it and when i returned it was like the pictures you posted. But this case was different. I died and when landed all my vehicles where missing, not underground but really missing. They were not there.
Since now i'm lost and i'm trying to find my base i can say if that happened again. But it was really annoying, since i gattered the materials and had the vehicles, just to find they where gone.
By the way, i'm playing on a laptop, Asus K53S, 6 Gb Ram and Nvidia Geforce GT 540M (forgot to mention before)