Scobrea
I ran into this problem before but I can't remember why it happens. I changed the project tempo from 120 to 150 however halfway through my project it changes back to 120...so frustrating!!! HELP!
You either have an event throwing a tempo change, or (maybe) you have inserted something that has its own tempo assigned (maybe a loop, step sequencer, or something) at that point. Should be fixed by having it follow the project's tempo. (A checkbox somewhere.)
Brian