Error message when you try to edit an Office document in a document library: "'Edit Document' requires a Windows SharePoint Services-compatible application"

Had an email from a colleague about a user having the  'Edit Document' requires a Windows SharePoint Services-compatible application error tryign to open and Excel file from sharepoint 2010.  Below is my response (names and some other details have been removed to protect the guilty and maintain confidentiality):

we had something similar last year, but bear in mind that our Sharepoint site is 2007 rather than 2010.  Solution was to install and enable the Sharepoint support addon for IE.  For more details see Microsoft Knowledgebase article 833714 (http://support.microsoft.com/kb/833714/en-gb),

I did a bit of research from home last night.  There are a few different possible causes:

• MS Office is either not installed or is a broken install (typically the person installing decided to leave some things out or some parts of the install were removed to free up space or resolve an issue)
• Trying to use a browser other than IE (e.g. Firefox, Safari or Chrome) to access Sharepoint (there is a plugin for Firefox).  I note from the screen shot that XXXX is using Firefox.
• The sharepoint site is not a trusted site in IE.
• Using IE 9 Release Candidate (i.e. post-Beta, ironically the Beta worked but one of the fixes when Microsoft moved it from Beta to RC broke sharepoint integration)
• Using IE as an embedded browser in [Mail Client] (depending on your settings if you click a link in [Mail Client] it either opens a separate browser window or opens the browser in a tab in [Mail Client], this latter causes a whole heap of problems so people should really set [Mail Client] to open the browser in a new window)

As XXXX is using Firefox I'd recommend she try again in IE, hopefully that will resolve the problem.

It appears (http://msdn.microsoft.com/en-us/library/ff407576.aspx) that the Sharepoint 2010 Firefox plug in part of Office 2010 so to use Firefox XXXX will need to install Office 2010.

If XXXX still cannot open the file after switching to IE I'd recommend:

• Check which version of IE she is using, if it's 9 downgrade to 8  or 6
• Check that the sharepoint site is in the trusted sites list
• Check if she can open other files and if other people can open that file (rule out it being a problem with that file)
• If all else fails, remove and re-install office.  Do a complete install to eliminate the chance that it's a problem with a vital component being left out.