If you try to open an Office document on a SharePoint document library and the document only opens in read-only mode or if you get a "The document could not be opened for editing. A Windows SharePoint Services compatible application could not be found to edit the document." error when you click on the "Edit in …" item on the documents menu, it means that the hotfix at http://support.microsoft.com/kb/938888 is missing on the client machine. To download and install the hotfix or getting the latest updates from Microsoft Update will resolve the issue.
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