Incomplete lexicon?

[S-P4-RK]

I recently got both myself and a close friend this game, and ran into a problem when comparing solutions to puzzles that we both had already completed. The methods that I used would not work for her due to missing words.

Not just any missing words either, common items like 'clock', 'watch', 'dagger', 'knife', &c.. My own game had no problem, and I pulled up even more obscure items such as a dirk without any trouble, while she was almost stopped in her tracks several times by words simply not being in the game where they should be.

I'm currently fixing the problem by having her delete the game's internal bits and verifying the game cache so that Steam re-downloads the lot, and so far it appears to have worked.

Has anyone else had this problem, and is there any way to prevent it should I wish to give the game to another friend?