Not sure if the following will help or not but here is one issue I have delt with. Also once we installed MS SQL 2008 R2 vice SQLEXPRESS the software is running much faster and better and the jobs kick of faster. I ran into an issue similar to the one you referecne above and the only way out was to build a new database which is a pain. In fact it is easier to just uninstall everything and start over.
One of the issues I have run into with DS7.1 SP1 W/NS7.1 is that if jobs dont complete or hang up eventually you have to clean out the SBSSTORE. I have even started doing this on a regular basis and it seems to make things work faster. You definitely have to clean it out if a job hangs and it keeps trying to execute on a computer.
to do this go to: <- on the server hosting DS7.1SP1
c:\program files\altiris\altiris agent\agents\deployment\Taskhandler\SBS\SBSSTORE
Delete all the files
then go to the Symantec Management Agent in the System Tray and open it up
then on that Click on Settings and click on Update in the window that pops up
then go to services and stop the 4 Symantec Services that have names starting with _SYMANTEC, stop them from top to bottom, then start then from top to bottom. DONT RESTART but STOP and START
Monitor the SBSSTORE Folder and it should repopulate with 3 files.