[kadet.89]

I'm away now, can't share the code. But it's as simple as possible.
There is a player spawn hook with a 5sec timer. In the timer callback function the player (if still exists) is given 1 such item. I get the index, but don't do anything with it.
I doubt that it is possible to create such a serious bug with sourcepawn code. That must be something wrong on the engine level. Beside, I have other plugins wich use GivePlayerItem with other item types and it doesn't lead to this problem.