You access this directly from the USB drive or copy it to the hard drive?
Right-click on the root of that data file and choose "Close .." Before you
shut down Outlook or disconnect the USB drive (assuming it is on it) and see
if helps.
If you access the file from the USB drive then ensure you also disconnect
the USB drive before unplugging it.

--
Bill R
"Arthur" wrote in message
...
I have an Outlook Data File (not the initial .PST) where I organize all the
message I want to keep. Since I work both at my business and at home (yes ,
I know :-), I have placed this data file on a U3 Flash Drive that I can
easily carry around with me.

All seems to work well, except that each time Outlook is launched, it
complains about the data file not having been closed propoerly the
previous time it was used. I never had this problem when the data file was
on a USB hard drive.

Anybody knows what is going on?

Thanks,

Arthur