Ron Rosenfeld laid this down on his screen :
I've never had that problem with 2007, but I have had it with other programs.
What has happened is that the association between the file extension and the
corresponding program got broke.
Here's a MSKB article that should help:
http://support.microsoft.com/kb/2464297
Well, Excel2007 opens but the file doesn't. That suggests the
association is not broken between the registered file type and Excel.
It does talk about multiple installs, though, but only refers to a
single version. I have Vs 8-12 installed on this machine, though I
suppose I could remove Vs 8/9 since none of my clients use either of
these anymore.
Some behavior observations:
Having Vs <12 running, I can open files from WE in the current running
instance.
Having V12 running, I get another instance of XL12 with the file not
opened. Looking into this further I find that
'IgnoreRemoteReqests=True'. I set this property to 'True' when my apps
run in an automated instance, and restore the original setting at
shutdown. Obviously, on this machine that's been screwed up due to
testing. I don't get this behavior on my test machines.
Resetting the property to 'False' and opening a file from WE behaves as
expected. Problem solved at my end!