cannot stop Task at 21%

I have a problem with a Full Backup Task.

It runs since 4 month and sticks at 21%.
The task is not shown under the appropriate Backup Plan and Tasks from this phisical Server.
Not elsewhere either.
In case of data loss I Backuped the Volumes manually with local Backup in Acronis.
This Task runs well I think.

There is a nother task stick to 0% (ExportTask) wich is not shown under any sections.

I cannot stop this two tasks.

A few time ago we have Problems with Backup because of full depots.
Deleting of old Backups did not work either. Somebody had turned on the recycle bin.

Is ther a posibility that this have got something todo with this new problem?
Maybe a databse is not refreshed because of this?

There are different errors in the Log.

After restarting of the server the Acronis Management Server Service did not start automaticaly.
The Log Entries:
The statement has been terminated
Violation of Unique Key contraint PK_Slice cannot insert duplicate Key in object dbo.slice

was created.

How can I stop and maybe delete and make new Tasks for the FullBackup Task and the Export Task.
Thanks for help.

Kind Regards,

Daniela