Mountain Lion asking for passwords on network?

This is driving us nuts in our home-office.

On one iMac (#1) we have our invoicing and accounting files. Machine 2 (#2) accesses these files over wired LAN via TimeCapsule as needed.
HOWEVER... since updating to Mountain Lion when #2 tries to open the shortcuts to these files on #1 it asks for passwords to access #1.

Now this is no great problem, just an annoyance as it never used to do this & there is no logical reason for why it should be doing so.

Can someone please help out here with a solution? I'm getting really bored of annoyed phone calls saying 'What's the %$#ing password?'

And yes the box is ticked saying remember password etc but it doesn't do so.