I came across this problem when opening a Word file recently. Someone had sent me a Word document to edit so as usual I moved it to a folder on my PC and double-clicked to open it in Word 2010. The file opened okay but I noticed that, strangely, the file was called Document1 at the top of the ribbon – not the name of the file I had received. Okay, so I decided to save the file with a different name. I clicked Save As but Word offered to save it in Libraries>Documents, not where I had originally opened the file.
So I knew there was a problem, probably with the file name. I use xplorer2 as my file manager and when I looked at the file extension, it was in fact .dot not .doc or .docx. So this was a Word Template file. Sure enough, when you look at the file icon closely as shown above, there is a slight difference between dot and doc icons.
So if you are having a problem with a Word document opening as Document1, it’s probably a Word Template file so just save it as a doc or docx file in your work directory.