Comment 655 for bug 88746

Your conclusions look right. And they would explain the disk problems: Many EHCI controllers have a bug which causes them to temporarily drop data on one port when a device on a different port disconnects. I'd say that whatever is causing the keyboard communications to drop out manages, every so often, to interfere with the disk traffic.

The computer then tries to reset the disk drive, but many USB drives have a bug which prevents them from resetting correctly when they're in the middle of an I/O operation. As a result, the drive becomes unusable and the system puts it offline.

As for what causes the keyboard problems... I don't know. It could simply be a cabling issue. For example, I've got a USB-to-PS/2 keyboard+mouse converter. It doesn't work at all when plugged directly into my computer, but it works just fine when connected through a USB extension cable. Try and figure that one out!

You could try using a different keyboard. Maybe it wouldn't get all those communications dropouts when plugged into the DLink hub or the ATEN switch.