An infamous "invincible library boss" for Carnby seems to be constant in this version. I did stumble on the glitch few times before (along with the ridiculous final Aline boss hit detection) on PS1 or old PC releases, but it usually went away if i left library after loading save and then returned. Here the flying bastard seems to be constantly invincible. He usually has to go down after about 3-7 rockets in the "vulnerable" state. Well, he doesn't

It's about timing. Maybe you shot these rockets a bit too soon (or too late). What weapon did you used to put him in a vulnerable state (I personally used the revolver)?
And Obed isn't that hard. Use the Photoelectric Pulsar and you're set.

I always shoot once with revolver when auto-aim kicks in, then switch to rockets and wait for auto aim to kick in again. So he does gets sent flying across the room after i shoot.
Oh and Obed is easy, yes. It's just that you can hurt him only from far usually. From up close he seems to get hit, but he's not. That's what always bugged me in that fight.

Wish I could tell you how I evaded this bug, but yeah, it is possible to kill him. It's just that this weird glitch may kick in because of REASONS or it may not for the same or different REASONS. I wish there was a clear idea of what those damn REASONS are. But it is possible to SOMEHOW make this glitch go away. I vaguely recall, that I've just wandered around and next try he finally died. No idea what triggered that, sorry.

After trying loads of things, (including wandering off like you just mentioned), I just started a new game playing the female character. After let's say about an hour I saved and loaded up my library save. AND THE BUG WAS GONE!
I beat the boss with 3 pistol shots and 3 rockets and I am pretty sure at least one of each wasn't timed good. So if anyone encounters this, maybe starting a new game with the girl and then returning may fix it. Thanks for the reply!

Cool. It is a weird little bug, shame Darkworks would never be able to fix it or make a remake of the game like they intended, cause they've been gone for several years now. Would be nice enjoying the game without worrying about this weird thingy happening randomly:)

Here's an even weirder glitch for you guys... the boss doesn't even appear! I remember the "invincibility" bug from playing this game when it came out, and now I'm playing the game again through gog. But although I've done everything, including solving the other library puzzle, nothing happens when I push the four books! I know I'm pushing them in the right order and I know the boss is supposed to appear after pushing the third book, yet it doesn't. I pushed the fourth book and all the four dots are red - yet the painting doesn't open and I'm stuck in a very painful way...

Advice, anyone? Can it just be my game that has this glitch? Or has it do to with playing in Windows 8? Up until now the game has been running well though and I haven't had any resolution or other technical issues. Help appreciated!