I am running a desktop with an APC Backups UPS. I was not getting any error messages during the boot sequence.

Yesterday, I was logged in as user, and clicked on "home" when the screen locked and responded to nothing short of turning off the power.

After selecting "yes" to allowing Linux to check the file systems and fix the errors, I am now getting the message that /proc/acpi/event file does not exist during the boot sequence.

Linux does not seem to allow me to create any directories manually under the /proc directory, even when logged on as root.

Uninstalling and reinstalling the two acpi related programs from the Mandrake Control Center seems to have no effect in recreating the event file.

How can I fix this, short of reinstalling Mandrake, and does acpi even matter on a desktop, since most of the posts that I see regarding acpi relate to laptop battery management.

Nah, I think that desktops use APM instead, so you don't need the ACPI. At least in my case