Got a full walkthrough, here. I did enjoy it, and I will say I used snapshots, but then that was necessary in the end, since it would someetimes crash when I changed weapon! :o
Thanks for the feedback! BTW, did you make sure you did not press the pause key instead? By default it's the "N" key, next to the default switch weapon key "M"
Not exactly the same sound but yes, it beeps, while the music keeps playing. I hope that was what happened, I couldn't replicate the bug.. All in all thanks!