The preferences for Excel are stored as follows:
yourname/Library/preferences/com.microsoft.Excel.plist, where "yourname" indicates the home directory of the user.
This plist file is the one that you need to delete.
You mentioned that the finder reported that it could not find the application that created it. Did you get a choice, at that point, to find the application?
Also, have the icons for your XL documents changed in any way. Do they still look like normal?
Let us know
I'm on OS 10.3.6; new flat panel G5; have been running MS Office X with no problems, but suddenly none of my (many) excel docs. are recognizable - message says it can't find application. I removed Excel and reinstalled, but it crashes immediately. I've checked for updates on MS but nothing seems applicable. Is there some preference file I need to remove that might help? Strange thing is that everything is still working fine on my iBook laptop - so far!
Other question: when I wake my flat panel from sleep, the screen flashes on bright, then blacks out completely, then comes back to full power. Does this happen to everyone?