Cannot restart 24x7 Scheduler GUI

I am using the 24x7 Scheduler Multi-platform Edition version 6.2 Build 657 and it is installed in Windows 10.

When I start the 24x7 Scheduler in GUI mode from desktop shortcut, it is fine.
But when I close it and start it again, it will display error message.
So this makes me cannot start the 24x7 Scheduler in GUI mode until reboot. Any idea for the cause? Thanks!

Error message:
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Error occurred during 24x7 Scheduler data initialization: java.sql.SQLException: DERBY SQL error: SQLCODE: -1, SQLSTATE: XJ040, SQLERRMC: Failed to start database 'DefaultJobDB' with class loader sun.misc.Launcher$AppClassLoader @ 1f96302, see the next exception for details. ::SQLSTATE: XSDB6Another instance of Derby may have already booted the database C:\24x7\JobDb\DefaultJobDB.

It sounds like the shutdown wasn't clean or didn't complete. Please enable the tracing option, reproduce the issue, and share your debug.log file with support.

As an alternative, open up task manager and kill the Java running task, then try again. Or just restart the services. I get the same thing, it does not cleanly shutdown every time.