It happens randomly to get one shot killed (even when i have full health) by normal enemies.
This doesnt make any sense so i think its a bug, but asking here to make sure.

I know this comes late, but yes it's probably a bug. I remember being very hard to die on that game, specially against normal enemies. Probably the only game where health packs come running towards you.

First time I've played the game, and it just happened to me. 100% health, feeding on a bad guy, another bad guy came running out and I was instantly dead.

Well, it's probably a bug, dying in that game is pretty hard. Unfortunately, I have no fix for you. Maybe contact support?

It is a bug indeed, when it happens it sounds like...50 hits in one second, first i thought it was just a sound distortion.
On my system (win7 64bit) it happens on both the GoG and boxed versions.
The good thing is that it happens randomly and rarely so its not game breaking, just a tad irritating :P

Yeah, that happened to me twice on my Windows 7 box.