What is this error message with no sense??

[tuomasvirtanen.net]

Every now and then I get from PS an error message: Couldn't open XXX because an unexpected end-of-file was encountered. OK. I did not meet that unexpected event before I wanted to save file. To me, this is ununderstable. I was working with PS as usual. What is this? I can loose a lot of work, as I'm not able to save a photo.

[Stephen_A_Marsh]

An unexpected EOF when opening usually means that the image is corrupted, it was incorrectly written.

You can always try other software to see if it can be opened.

If you are saving over a network, then that is a common reason.

[Trevor.Dennis]

If this is happening intermittently then you have a problem. Either your operating system is sick, or hardware has an issue or, as Stephen suggested, your network connection is problematic. It's something you need to get on top on for sure. 

[tuomasvirtanen.net]

Thanks! I now work with files on my Macbook, save them there temporarily, and just save the final files to my iMac (my network :).