scott41 : in app manager, use the Tools menu and access the log file (journal). Lines starting with "E:" are errors. See if anything complains about duplicate repositories or failing to access one. Then empty the log, go back to Tools then to the repository manager. Disable any repo that generates errors or looks like a dupe. Then see if app manager is back to normal.

I had this yesterday, dunno if it's due to maemo mapper or Canola as I updated both at the same time, but the above did the trick.