For some unknown reason, when I work on an assembly and save it, then reopen it, I am getting what seems like random mating errors. My assembly is all over the place and it is saying no solution found. I don't know why this is happening. Even if I over defined the assembly by adding two similar mates, or if I made two conflicting mates, I don't understand why all the unrelated mates would suddenly fall apart. I have been through each mate over and over to try and find it, and tried using Mate Xpert but I really don't know what is going on. I was hoping someone with a bit more experience may be able to have a look at the assembly for me and tell me what I am doing wrong, or why this is happening.

The file is Solidworks 2016 Mate problem.zip - Google Drive

Any help would be really appreicated