Microsoft Office document is "locked for editing by 'another user'"

Straight from Microsoft KB 313472:

This behaviour may occur if Word determines that the owner file for the document already exists. This may occur if one or more of the following conditions are true:

• Word previously quit improperly and, therefore, did not delete the owner file. -or-
• A second instance of Word is running in the background with the document already open. -or-
• The document is shared over a network, and another user has it open.

From my personal experience, I've found a combination of the first and third point above can recreate this error quite constantly.

Temp files, left next to the original file on the network (especially if the file is large, she copy-pastes a LOT or it is open all day) are the cause.

To resolve this issue, first confirm that another user on the network does not have the document open. If the document is in use, open the document as read-only. If it is not in use, quit all instances of Word, and then remove the owner file. To do so, follow these steps.

NOTE: Because there are several versions of Microsoft Windows, the following steps may be different on your computer. If they are, see your product documentation to complete these steps.

1. Quit all instances of Word. To do so, follow these steps: 1. Save all your work, and then quit all programs. 2. Press CTRL+ALT+DELETE to open the Windows Security dialog box. 3. Click Task Manager, and then click the Processes tab. 4. Click Winword.exe, and then click End Process. 5. In the Task Manager Warning dialog box, click Yes. If you receive a message that states that the program is not responding, click End Now. 6. Repeat steps d and e for each occurrence of Winword.exe. 7. On the File menu, click Exit Task Manager.
2. Start Windows Explorer, and then browse to the folder that contains the document file that you tried to open when you received the error message.

3. Delete the owner file.

   The owner file is located in the same folder as the document that you tried to open. The owner file name uses the following convention: It begins with a tilde (~), followed by a dollar sign ($), followed by the remainder of the document file name. The file name extension is .doc. For example, the owner file for Document.doc is named ~$cument.doc.

4. Start Word. If Word asks you whether you want to load the changes that were made to the Global or Normal template, click No.
5. Open your document.

Additional note for documents shared over a network:

If there are multiple people that could be editing the doc, it can sometimes be hard to figure out who might have the doc open. As shown on TechTalkMadness, the best way to find the answer is to use Computer Management on the system that hosts the shared file.

Go to Computer Management -> System Tools -> Shared Folders -> Open Files to find out who has a document locked. If the user can't be contacted to disconnect themselves, you can forcefully do so by right clicking the locked file and selecting Close Open File (warning: the user might lose their changes).

Try turning off "Details" and "Preview" in explorer

I just had this problem and the MS knowledgebase article was no help (tell other users to close the document? This is a shared Excel workbook, they're supposed to be opened by multiple users!)

Anyway what solved our problem was by turning the details tab off in Explorer (this is under Windows 7 - click Organise where the menu bar is normally, then Layout, then make sure Details is unticked - and also Preview by the sounds of it.)

Doing this immediately fixed our problem. It seems that with the details tab visible it keeps the file open for too long and Office apps can't then access it. This also explains why people were having problems opening documents they had created themselves and nobody else was using.

Try turning off the Indexing service

I had this and resolved it by turning off Indexing Service in Windows. The effect was instant, so I suspect Indexing service had deadlocked on the file in question.

On XP, Turn off indexing service like this: click the Start button, then Search. From the window that opens, choose Change preferences (bottom left). Click "Without Indexing Service", the "No, do not enable Indexing service" radio button, and OK.

I found the problem by downloading handle.exe. handle.exe tells you which program has the file open, and in my case it turned out to be cidaemon.exe. A quick google confirmed that it is the actual indexer of Windows' indexing service.

Thanks Microsoft, another 2 hours of value added to my day.