Installing MSN Messenger on W2K SP4

I'm having problems trying to install the MSN Messenger (Version 5.0 - English; 6.0 - English and Portuguese) on Windows 2000 with SP4. All the three versions result in the following error message during the installation:

"The installer has encoutered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2203."

And then, after closing the installation software, it gives another message:

"MSN Messenger Setup has failed with error code:'1603'. Please go to the MSN Messenger Web site and download the software from there."

The strange thing is that I downloaded all versions from Microsoft's Web site.

Besides, I'm the OS adminstrator, having privileges on W2K to Install any software.

We (my company) were trying to use MSN Messenger as an internal source of communication, due to it's simplicity and potential. If anyone has any ideia, I'll be very grateful.

Marcelo