LibreOffice 3.3- General input/output error.

Hello guys,
I am writing an article about my project to my company, but suddenly when I tried to save the document this error appeared. What does it mean about input output error?
I am not a technical person so I don’t have any idea how to fix this problem.
Please help me.

LibreOffice 3.3
Error saving the document Untitled1:
General Error.
General input/output error.
