I've not used Report Explorer, but I'll make a guess, FWIW.
Have a look on the W2K system and see if Report Explorer has stored the password in a security related options dialog.
But even it does appear that there is a password cached, it might not be displayed regularly (and would therefore be unreadable), so you might not be any further ahead.
You might be better off to contact Datawatch support directly to see if they have any tricks to handle this situation, though Report Explorer is an older product and may not be currently supported.
Please let us know how you progress.
The password might just be Vista wanting authority to run the application? I doubt that Report Explorer is supported on that operating system, as it was released about a decade before Vista was developed...
If your users need to view reports I'd suggest using the feature included since v9 of Monarch, to export the report as a PDF file with the tree definition embedded as bookmarks within the PDF file.
If you'd like to see an example PDF like this please feel free to email me a report and model file.
I was having the same issue. I just got it to work.
Even though I typed and retyped several times the password that we're given and have been using it would not work. On a whim I typed the password without any capital letters /Uand all reports started opening fine.
Since it gave me such a headache I'm making sure to come back and post the solution that worked for me.