We created a document library in Sharepoint 2010 and configured it to require checkout. Via Internet Explorer, users click on a document in the library and choose "Check Out and Edit". They get the error message "This document could not be checked out. You may not have permission to check out the document or it is already checked out or locked for editing by another user". We confirm that the document is not checked out to anyone else. The user is able to open the document Read Only from IE and then check it out in the application (for example, they can click the Check Out button in Word 2007 successfully), so the problem seems to be IE related. We have tried adding the Sharepoint site in the Trusted Sites and Local Intranet zones in IE, but it doesn't make a difference.Any suggestions?Thanks.
View Complete Post