I tried to check in the file to the site. But I got this error message
(The system cannot find the file specified (Exception from HRESULT: 0x80070002)).
I'm able to check out the file, edit, and even save the file successfully. I never have this problem before. I'm not sure how to fix this.
This is my environment: SharePoint 2010, Office Standard 2007, Windows 7 Professional (Build 7601) operating system and Internet Explorer 8.
This is what I have for the IE addon:

I do not have Microsoft SharePoint Foundation Support install in my Microsoft Office.