Unable to Save Workbook In Excel 2004


My system:

PowerPC G4 450 (Sawtooth)
640 MB of RAM
Radeon 8500 w/ 64 MB VRAM
18.84 GB available on boot partition
2 other partitions with at least 15 GB available
Mac OX X 10.4.2 (8C46)

My Problem: When attempting to save an open workbook in MS Excel, I am given the follow message:

"Microsoft Excel cannot open or save any more documents because there is not enough memory or disk space.
*To make more memory available, close workbooks or programs you no longer need.
*To free disk space, delete files you no longer need from the disk you are saving to."

As previously stated I have plenty of disk space to store a measly Excel file. I am not given an option as to where to store the file. As soon as I try to save the spreadsheet the cannot save dialogue box appears.

RAM shouldn't be an issue. Initially I had maybe 4 or 5 programs open. I closed ALL of them except Excel and Dashboard - problem still occurs.

I don't know whether this is relevant or not but this was the first time I have opened Excel 2004 on this computer. I previously had Excel v.X and it worked fine. That was removed and the Office 2004 suite was installed about a week ago. MS Word saves without a hitch.

Hope you guys can help. I'm stumped. The spread was for a college assignment. I have to take a screenshot of the workbook in order to turn this thing in.

Thanks in advance.

P.S. I attempted to research the problem myself using Microsoft's support "Matrix". No help there.
Dump the preferences.... *username*/Library/Preferences/Microsoft/com.microsoft.Excel.prefs.plist. Put that file in the trash, without deleting... Make sure Excel is not running. Don't have to, but you may as well restart the computer. Re-launch Excel.. see if the problem still exists.