Microsoft Access Database Engine error '80004005'

Could not use 'C:\inetpub\websites\1601_tangerinedream.org\wwwroot\Data\DataBase\db_struktur.accdb'; file already in use.

C:\INETPUB\WEBSITES\1601_TANGERINEDREAM.ORG\WWWROOT\SHOP\EN\LIB\../../../interactivist/library/d_allgemeineroutinen_frontend.asp, line 900