CDO .Send fails on XP SP2

I have written a VBScript sub that uses the CDO object to build and send an
E-mail under program control; the script makes a connection to our local
Exchange 2000 Server. The sub has worked fine in production use for a year
now, but it fails on a test XP SP2 machine, with the following message.

Error = IDispatch error #19
Source = CDO.Message.1
Description = The transport failed to connect to the server.

I have done my best to search the KB for info on this error, to no avail.
Any help is greatly appreciated! I have also searched for a newsgroup
specifically addressing SP2 issues; I did not find one, so I have posted this
question here. Is there a better newsgroup for me to use?

TIA...

Sorry - false alarm...

It turns out that an associate had recently installed McAfee VirusScan
Enterprise V8, and this program requires that application programs be
specifically authorized to use port 25 to send E-mail. Once the program
running my scripting was authorized, the problem went away.