TweakUI may have been the culprit. Some of its functions
require modification of the "c:\msdos.sys" file, so it
disregards the attributes. The version I am using is
somewhat cryptic in this particular item, displaying it
innocently under the "Boot" tab as "Start GUI automatically".
If this is unchecked, the computer will boot to a C:\ prompt,
without even telling the user how to start Windows or
reverse the change.

Ben

"ms" wrote in message ...
I recently had a machine where bootup stopped at a C prompt because of
this.

The msdos.sys file is hidden, the attribute is read-only. Yet a sound card
install apparently changed the default BootGUI setting from 1 to 0.

Changing it back restored the system.

How can any program write to a read only hidden file?

ms