Apple is aware of this problem, which has to do with a patch to the "Open"
trap for the Slot Manager. The Slot Manager assumes that all attempts to
open a file that has a period ('.') as the first character in its name is a
driver for a NuBus card.
This will always be a problem with System Software 6.0.x-based Macintosh
systems. There are no workarounds that we are aware of except not using a
period as the first character in a file name.
System Software 7.0 has a call that prevents this problem from happening.
The call that causes the problem is "FSOpen". The new call is "OpenDF" and
will be documented in Inside Macintosh Volume VI. The difference between
the two calls is that FSOpen can open both files and devices; OpenDF can
only open files.
This problem will still happen in System 7.0 if the old call is used. This
will be the case with all existing applications and possibly new
applications for System 7.0 specifically. Both calls will work under
System 7.0. We recommend that developers use the new calls for their
System 7.0 applications.