Error Message: "xis is not a valid Win32 application"
 

I have installed Office 2003 Pro with Front Page on my XP system.
Due to some problem with Office is uninstalled the software and reinstalled
it again on my XP system.
Now when I try and open an old spreadsheet I get a message "xis is not a
valid Win32 application".
The only way I can open up the spreadsheet is if I keep the install disk in
my CD.
or with the Microsoft Excel Viewer.
If I go to Programs and just try to open the software for Excel I get
another message "The feature you are trying to use is on a network resourse
that is unavailable" and then the bottom of this messages says:
"Click OK to try again or enter the alternative path to the folder
containing "PROPLUS MSI"
Can anyone help me understand what I have to do to correct this problem.