I stumbled onto this little piece of info while researching an unrelated connectivity problem. Oracle changed an encryption algorithm they use (for at least Access Id/Password) a few months back. This change went in with PeopleTools 8.52.24, 8.53.17, and 8.54.04. Most places I’ve been have always kept their PeopleTools clients at the same level as the Tools release in the PeopleSoft Database. But I have seen on more than a few occasions, either certain users lag behind or the updated client is not pushed to developers. This happens sometime for those doing minor release updates. When going from a level lower than the three listed above to a level equal or higher than listed, clients will no longer be able to connect. They will be greeted with an Invalid User ID and password error.