You can use the sp_resetstatus system proc. That will try to force the database online/healthy. You have to stop/start the server to take affect, which may be a problem from what you said.

...If that doesn't work, you can force the DB into emergency mode by setting the "status" field for that DB in sysdatabases to 32768. MAKE SURE TO NOTE WHAT THE STATUS WAS BEFORE YOU CHANGE IT! You must also bounce the server for this to take affect. Note: you must "allow updates" to system tables before updating the status. This method is undocumented and is usually a LAST RESORT if you must get the data out of the database.

BTW, I'm not sure if this will work for "msdb". Also, any idea what caused it to go suspect...hardware/disk failure?

-Dan