Plex playing the same (wrong) file for multiple movies?

Using the latest version on Windows 10 64-bit, latest version of Firefox and Galaxy Note 5 on the latest version of Android available.

The other night I was watching a movie and when I went to start another, it started playing an entirely different movie (Trailer Park Boys (1999)), with Finding Dory’s poster as the Chromecast backdrop. I figured the file for the movie I wanted to watch was corrupted, deleted it and redownloaded it. Same problem. I figured then that it might be the filename of the TPB '99 movie since there’s an identically titled movie from 2004, so I deleted the 1999 TPB and tried again. The same thing is now happening with a different TPB movie. Investigating further I realized it wasn’t just the one movie I wanted to watch that was redirecting to TPB, it was a handful of them, with no rhyme or reason to it. Tried deleting the Movies folder and remaking it. Still broken. Tried using the “repair” function in the installer and rebooting. Still broken. The filepaths in the movie info still point to where they should be, and when I open the files in VLC and MPC they’re fine. Oddly, I think my TV show folders are unaffected.

oh and i tried rescanning my library multiple times

UPDATE: I’ve found a way to bypass it by starting a different movie, adding the one I want to watch to the queue, and then hitting next. The movie then plays properly. It still plays TPB when I try to watch it the other way, though.

Sounds like you activated Pre-movie trailers and/or a ‘Pre-Roll’ video.
https://support.plex.tv/hc/en-us/articles/202920803-Extras