I was recently setting up a new ASA 5505 unit from a backup configuration file and after restoring the backup through ASDM I could not connect back again using ASDM.
I received the error message: Unable to launch device manager
Command line console was ok.
Worked out in the end that I had upgraded to the latest ASDM version on the 5505 but when it re-booted it picked up the old original ASDM file as the one to load (this may have been due to not saving the configuration before restoring).
In the command line I just had to set the ASDM version back to the newest version:
Config T
asdm image disk0:/asdm-???.bin
e.g.
asdm image disk0:/asdm-713.bin
Then do a:
write mem
You should now be able to logon to asdm as normal.
IslandEarth 