"Microsoft Access will not open the file" bogus error

[planetearth]

Full error message:

"Open File - Security Warning
Name: BMT.mdb
Publisher: Unknown Publisher
Type: Microsoft Access Application
From: C:\BMT
Open Cancel
Always ask before opening this file
While files from the Internet can be useful, this file type can potentially
harm your computer. If you do not trust the source, do not open this
software. What's the risk?"

After clicking Open:

"Microsoft Access
Microsoft Access cannot open this file.
This file is located outside your intranet or on an untrusted site.
Microsoft Access will not open the file due to potential security problems.
To open the file, copy it to your machine or an accessible network location."

I'm getting the above error when I try to open a file on a Windows XP SP2
machine with Access XP. The file opens fine on another Win XP SP2/Access XP
system, and in both cases, the file is local, in its own folder.
Nothing on Microsoft's site suggests why I might get this message in error,
only that I'm trying to open the file across a network or the Intranet.
Neither is the case, here.
I've added Access to XP's "Data Execution Prevention" list, but that did
nothing.
Has anyone else had this, and if so, what can I do to fix it?
Thanks.

-Steve

 

[planetearth]

The paths are exactly the same (just on different computers). Both sets of
files are on the hard drive, not a CD.

 

[planetearth]

Joseph,
Thanks again for your replies, but again, everything is exactly the same
between the two computers. Also, this worked just last week, before the file
had a minor tweak applied to it (to refine error checking in the database).
Now, the same database works on one, but not the other. Nothing in the path
structure or permission structure has changed. They're the same on both
computers. The only thing that's changed (slightly) is the file, and unless
Access or Windows is preventing the file from running, I can't imagine what
else it might be.
Thanks again.