After install from asg-7.350-081120-2.iso, initial reboot, and logging in as admin, one is presented with:
Continue with this Wizard
Restore Existing Backup File
If one restores from a backup, and the backup is encrypted, the result is a "corrupt backup" dialog.
The same configuration works without encryption.
If one Continues with the Wizard, he can then restore from the same encrypted backup file that failed earlier using the Management->Backup/Restore->Import function.
This log might be a clue:
2008:12:04-20:04:19 (none) confd[4588]: id="3100" severity="warn" sys="System" sub="confd" name="SNAPSHOT_ADD_FAIL (Adding (uploading) snapshot failed)" client="index.plx" facility="webadmin" user="admin" srcip="192.168.223.15" text="backup corrupt" perl_error="Storable binary image v41.97 more recent than I am (v2.6) at ../../lib/Storable.pm (autosplit into ../../lib/auto/Storable/thaw.al) line 363, at /PerlApp/Snapshot.pm line 241"