Sorry it took me so long to reply to this. Had several things come up that prevented me from checking out the system.

I couldn't find the key in the registry regarding the filters, so I started looking at other things. I then discovered that the DVD drive appeared and worked correctly in safemode. So I disabled a couple of startup items, [Kaspersky, SB S&D Teatimer, and Malware Bytes {Full paid version}] and rebooted.

The DVD drive was back. So I started enabling those items one by one...

first Kaspersky, rebooted... still there.

Then Spybot, rebooted... still there.

Then Malwarebytes, rebooted... still there??

I showed the owner of the system how to disable startup items, and told him that if it happened again to disable those one by one, rebooting each time. That was on Saturday, and I haven't heard from him since. Not sure that it is fixed... but it was a daily occurrence before that, and I told him to call me if he had any more trouble, and that I would take another look free of charge.