Cita: This is almost always a permissions issue. Be sure that the MDB file is in a folder where IUSR_<machineName> and IWAM_<machineName> have read/write access (because the anonymous user needs to create an .LDB file when modifying the database). If you are using Windows Authentication, make sure all authenticated users belong to a group that has read/write permissions on the folder where the database exists, and if you can't use a group, step through each user and check that they have sufficient privileges.
Cita: Of course this error could also happen if you're storing your Access database on a floppy disk that has write protection enabled (or that is full). Please don't do this; using Access is inefficient enough. You don't want to add floppy seek time to your performance issues.
Casi siempre salvo en casos muuuyyy especificos, este error es de permisos, "revisa bien tu codigo" bah!
Imprime el resultado de esto: Server.MapPath("productos.mdb")
Y asegurate que la ruta sea correcta, pero de nuevo esto casi siempre tiene que ver con el usuario que utiliza el IIS.
Como te dije antes, hay muchos posts al respecto aqui mismo, buscalos, porque en casi todos se da con la solucion.
Salu2,