Documents read only

I’ve been experiencing some problems with office documents on a Windows file share.

An user is reporting that he gets allot of messages that the file is in use and it is “Read Only” .

It’s only possible to open a copy of the original document. This issue does not exist on Windows clients.

By checking the Open Files on the Windows server and the running processes on the Mac I Have noticed the following:

• When the preview screen in the Finder is active the document it is shown as an open file on the Windows Server, when the image is loaded it’s no longer open.
  It’s no problem to wait on this process but the problem still occurs even if the process is finished or the preview screen in Finder is not active.
• Sometimes when I open an document it will show 2 sessions of the same user/document in the Open Files. When I fully close Office the sessions are still open. (even if al office processes are killed). So I have to force the session to stop on the server to access the documents again.

I stopped bothering the user with this and started testing on my own Mac.
I had the same problem with the “Read Only” files.
Office 2011 (latest updates)
Os x Lion 10.7.4 (latest updates)

I’ve tried the following that didn’t help.
- Disable Spotlight indexing on the network drive (not that it works Anny ways).
- Latest updates of OSX and Office.
- Deleted user Office plist files.
- New office Database.
- Disable the lock files in Time Machine.
- Disabled recent documents (as well OS X as Office).
- Reconfigure the rights on the documents on the file server.
- connect as different user.

At First I was testing with my own Windows Domain account (local home folder). so I created a fresh new local account with administrative rights. With success because the problems were solved.
Next I started with a new Windows Domain account and also had no problems, of course the documents are “Read Only” when the preview windows isn’t finished.

In the console logs I cannot find anything regarding this problem.
Is there anyone who also experiencing this problems? Or knows the solution or why this happens?