Problems Installing Windows Installer 3.1

Having problems updating Windows Installer 3.1. I double-click on
update, install screen appears for a few seconds, then come the error
message:

"The system must be restarted before installing the KB893803v2, to
allow some prior file update uperations to complete. (These operations
were previously scheduled by some other install or uninstall
operation.)"

I really have no idea what it's talking about. I've tried rebooting,
installing in safemode, and typing in "msiexec /unreg", then "msiexec
/regserver". The strange thing is, the temporary files for the update
appear in my external driev, not the one that Windows is installed on
(I have Windows XP).

This is what the error log (C:\WINNT\KB893803v2.log) says:

0.063: 2005/10/26 18:32:55.522 (local)
0.063: d:\6066cf513c460b58ee\UPDATE\update.exe (version 6.1.22.4)
0.063: Hotfix started with following command line:
2.453: KB893803v2 Setup encountered an error: The system must be
restarted before installing the KB893803v2, to allow some prior file
update operations to complete. (These operations were previously
scheduled by some other install or uninstall operation.)
3.406: The system must be restarted before installing the KB893803v2,
to allow some prior file update operations to complete. (These
operations were previously scheduled by some other install or uninstall
operation.)
5.047: Message displayed to the user: The system must be restarted
before installing the KB893803v2, to allow some prior file update
operations to complete. (These operations were previously scheduled by
some other install or uninstall operation.)
5.047: User Input: OK
5.047: Update.exe extended error code = 0xf02a
5.047: Update.exe return code was masked to 0x643 for MSI custom action
compliance.

Any suggestions? Thanks...