I saw a few people say that they had to drop their instances (or thought they did). An option is to issue the command "emca -x SID" This will remove the Database Control for that database. Then go into the database and manually set the passwords for SYSMAN and DBSNMP to something you like (and can remember). Then run DBCA and choose the reconfigure option. This will allow (by default, I think) you to put Database Control back in and set the passwords. Ensure you set them to the same passwords you just set in the database! When DBCA is done, you should be able to see your database status. This seems to be platform independent. I fixed my Linux instance.