Excel Slow File Open Directory Response

Whenever I am connected to a network - VPN or Home Network or anything - and
I want to open up and existing Excel file, my efforts to us File Open "Look
In" response is very slow. It is so slow that I sometimes double click it
and it comes back as "not responding".

This did not always occur like this and unfortunately I cannot track
something that I might have done to cause this but it sure is annoying. I
can only think that it is doing some sort of indexing (?) process that is
slowing it down. Or could it be Microsoft's own Spyware tool?

Any ideas? Thanks.