Try repairing Word 2003.
From
http://support.microsoft.com/kb/822005#13
To run the Detect and Repair feature, click Detect and Repair on the Help
menu in Word. The Detect and Repair feature fixes and repairs Word. All
files, registry entries, and optional shortcuts for all Office 2003 programs
are verified and repaired. If you run Detect and Repair from Word, all other
Office 2003 programs are also checked. This feature performs only a
checksum.
The Detect and Repair feature can also restore the Word program shortcuts on
the Start menu. To do this, click Help, click Detect and Repair, and then
click to select the Restore my shortcuts while repairing check box.
If Detect and Repair does not correct the problem, you may have to reinstall
Word. The Reinstall feature in the Maintenance Mode dialog box completes the
same action as Detect and Repair, except that Reinstall copies a file when
the files are of equal versions. Detect and Repair does not copy over the
file when the install file has the correct version and checksum.
Note The Detect and Repair feature does not repair damaged documents or a
damaged Data key in the registry or the Normal template.
If a file that Word must start is missing, the Windows Installer
automatically installs that file before starting the program.
How to install or repair and reinstall Office 2003 programs and features:
http://support.microsoft.com/?kbid=821593
For the other error message regarding Windows Installer, see:
"Error 1719. The Windows Installer service could not be accessed" error
message when you try to add or remove a program:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q315346