Anyone run into a situation where after you examine an item in your inventory it disappears? I'm going to uninstall and reinstall and cross my fingers but wanted to ask here first, thanks

I believe it is intentional so that your inventory doesn't clog up with items, for instance, all your faxes disappear after you read them, some items may be removed once a location is complete etc.

From my experience (I recently replayed the game) the vanishing items are not needed after they are gone.

Really? I guess the one that I thought was wrong was the case of 'drugs' you find at Carl Linksky's house at the start of the game. Its been years since I played but I thought you needed that later in the game. Is that not right?

I remember finding that (the syringe, right?) but I don't remember using it (other than looking at it), odds are it opens another 'Ask About..." option.

Yep, that was it. I could swear you used it to drug a gorilla with the bananas but that must be something else. I'll keep pushing forward, thanks!

You use something else with the Gorilla :)