I've been working for a couple of days on this issue and no joy. Please see the attachment, the error that I get is this:
C:\Documents and Settings...Outlook.ost cannont be accessed.
You must connect to Microsoft Exchange at least once before you can
use your offline folder file.
When physically connected to the network I'm able to stored a copy of my mailbox in the proper .ost , but when testing the offilne feature I get the same error as showed in the attachment. I even changed the location of the .ost to my documents and received the same outcome. I've recreated the outlook profile and the entire profile several times with no luck and removed and reinstalled office, and check permissions.
However,, I'm able to access my mailbox with no problem when accessing it over my VPN connection or with of course being physically connected to my network.
I followed this link to setup cache: http://office.microsoft.com/en-us/outlook-help/turn-on-or-off-cached-exchange-mode-HP001232935.aspx#BM5
but no joy.
One thing I did notice I was awkward, I tried to repair the .ost going to c::\Program Files\Common Files\System\Mapi\1033\sca
nost.exe but the scanost.exe was not there even after changing the settings to show hidden folders.
Please advice, Thank you