Thank you for the help everybody. It looks like I am running version 2.8. The file extensions is correct. Not sure how to locate the RC files that someone suggested I erase. I tried to upload the file and share it, but the forum uploader says the uploaded file is empty. This might be a clue.

Your gimprc file is located in the /USERNAME/.gimp-2.8 directory.
If the XCF workspace file is corrupt, and it sounds like it may be, removing the gimprc file will not help.

What is its size (in bytes). And what would be its expected size in pixels?

zero byte image= not working
good call that has to be the reason right? But what happend?

I have no explanation. If your disk is healthy (see SMART data) and the file system is clean, you could report a bug. I wonder if this could be due to two concurrent file save if you hit Ctrl-S twice, the scoend tile while the file is till being saved. Personally I have never experienced this and it seems to happen only to Windows users (but then there could be a bias since they are the vast majority of Gimp users).