When you open kettle (sorry Pentaho Data Integration), it is so polite to re-open the transformations and jobs you had open the last time you were working. A nice feature, however ...when kettle tries to open jobs/transformations with connections to a server that isn't available anymore (because I shut down my VPN or I switched location), it will try to find that server. And that can take a long time.
Example: Below I opened kettle with 3 jobs 'remembered'. Those jobs each contain 4 Oracle connections and 1 AS/400 connection. All connections are shared. The time that passes between launching kettle and getting the three error boxes is about 54 Mississipi :-). In the meantime you cannot do anything in the kettle interface. It doesn't react to anything until all error messages are on the screen. Knowing that I sometimes work on over 10 jobs/transformations, that sometimes makes a very long Mississipi.
In case you are confronted with this issue from time to time, the trick to avoid this kind of behaviour is so ensure that you have no network connection at all when you start up PDI. Unplug the cable or disable your wifi for a second, and that'll solve the issue. No more frustrated waiting.
In the meantime I have posted a Jira to ask the folks at Pentaho to make sure the time out happens a little bit sooner. A minor bug, in one of the major data integration tools [I tend to disagree with the Gartner boyz]:-)