@acer 

Thanks for letting me know, seems like you know what you are doing :)

However i don't think the issue is quite solved yet. I can download and open the file you sent me, which is great. However it seems like I keep reproducing the same error. So here is exactly what I've done.

1) I tried to make a brand new file where i copied the entire content of your recovered file in. Then i saved it, closed it and reopened it. Everything worked.

2) I wrote another chapter and maple started acting a bit weird. At one point i was unable to delete an empty line. I saved, closed maple and reopened. The exact same error happened and that file is now corupt. (However this is not really an issue as I still got your recovered document, which i quiickly made a PDF out of.)

3) I suspected, that somehow there might be a bug left in the document, and decided to manually, line by line, recreate the entire document. No copy pasting, simply write off what was already written in the other document. After each chapter i saved, made a backup and tested if everything worked. The first two chapters worked flawlessly I could and can still open those documents. But when i wrote the latest chaptet (Still by hand, no copy pasting) the issue came back! So somehow these spooky killer equations keeps appearing, and im honestly a bit terrified that they might come back when i'm doing any work in maple. 

I have added the three files below.

The latest one which has the error

solutionmethodssafe.mw

First backup which works

solutionmethodssafe_backup_1.mw

Second backup which works

solutionmethodssafe_backup_2.mw

Do you have any idea what is causing these issues and how i cna avoid them? I have also tried reinstalling maple, but the issue seems to persist.

Sorry to bother you once more, but hope you can help :)

@acer 

Wow, thank you so much! You litterally saved hours of work.

Just wondering. Is this something i would be able to fix myself? :)

Have a nice day and thank you once more!