I posted this issue before and thought I had this resolved but no joy << We have sharepoint services 3 and have been able to check out and check in docs from any of our doc libraries by using the dropdown menu for over a year until today. All of a sudden the check in option does not work any more on certain computers (office 2007 or office 2010). You have to select upload, browse for the document in the sharepoint drafts folder and then upload to be prompted to check in. The document then remains in the sharepoint drafts folder as well. Nothing has changed on our sharepoint site and all computers on the network have same settings (some win7 and office 2010, others XP and 2007. All running IE8. Not all computers are affected and the issue is computer specific not user specific. All updates are managed through group policy. Checked internet settings and all settings are the same on both the pcs that work and those that don't.>> I cleared the cookies and added to trusted sites. It worked from home last night from home, but back in the office this morning I have no joy. Problem seems to be happening while I am on the network inside work only.