500 error when trying to edit post or add new one

[eliquid]

I get a plain 500 server error ( non vbulletin error ) at random when I try to edit a tread or post a new thread with different texts. The texts are all normal ( no strange chars. ) and I am using the default theme and no plugins.

Its just very odd.. the text is also not very long.. ive tried posted long text and also short texts and sometimes I get the error and sometimes I dont. However, I've noticed this error more anytime I am trying to edit a current post and add more text to it.

Any clues?

Forgot to mention im on 3.8.3 and on a VPS with only this script on it