I've seen that happening when users save passwords ("Use a different user ID and password" option in the Connection Wizard) and change their Windows passwords and start using "Use my Microsoft Windows user ID and password" option.
2 ways to resolve this 9in my case):
1. Force users to use 2nd option (Enable SOX)
2. Go through the connection wizard choosing 2nd option and enter proper credentials (uncheck "Save password"); go through the connection wizard again and choose 1st option.
Hope that helps,
Akim