Fixing a broken Office Document Cache

So you are using Microsoft Sharepoint to collaborate with your friends.  You navigate to a document and select "Edit in Microsoft Excel" (choose your Office program of choice here) and Excel is launched, starts downloading the file and then pops up a dialog box to say:

Could not open 'https://yoursharepointserver.sharepoint.com/yoursite/Shared Documents/sales figures.xlsx'

Then you realise you are getting this error for every document you try and edit!  No other details, no feedback, nothing in the event viewer.  Internet search results all seem to send you down the trusted site, turn off security settings in internet explorer settings route, etc.  Well before you run your PC in 'please hack me' mode you might want to read on...

If your PC is like mine, your Document Cache is probably done for.  You might try deleting it using the Upload Center (Start > All Programs > Microsoft Office > Microsoft Office 2010 Tools > Microsoft Office 2010 Upload Center) as per these instructions from Microsoft.

You may just find that you get a screen like this:

Upload Center error screenshot

... and that deleting the cache in the settings screen causes the Upload Center to crash.  In which case, you will need these invaluable instructions from the (unofficial?) Microsoft Office Support blog:

Manually Rename Office Document Cache ~ Microsoft Office Support:

'via Blog this'