Playerstart Problem

I admit this is a newbie question. But I tried hard to find the error myself. Unfortunately without success.
My problem:
My player suddenly starts at a completely different place than the one defined in the player start. There he remains frozen. Delete the player start and insert a new one does not help. The player start has no error message. Viewportype is default viewport. Playmode is default playerstart. Everything else works fine. The error always occurs after some time in a level. Then I have to access the backup, because I can’t fix the (my) error anymore

I hope for a hint where I can search