I have 16 files that were added to our Team Foundation Server Source Control repo as part of a larger add/checkin that remain un-check-inable.
Nothing special about the files--text files, xml files, xls files, no funky names, and the Visual Studio 2010 Team Explorer check in hangs when either a single one or all are attempted to be checked in.
The add works w/o problems (though some but not all show as "add, lock" state?!). When Check In Pending Changes is attempted, and the files in question are selected, the check in dialog will hang at "Performing add on [first file in group of 16 that was selected for checkin]...". devenv.exe has to be killed to recover from the hang.
This is reproducible with the files in question (undo pending changes, add items to folder, check in pending changes).