Memery Card Reader Issue

Today I moved my computer and peripherals into another room.

I have use the same card reader for maybe 6 years without issues. Suddenly I can't get most cards to mount. Instead, the card reader's green power LED and the red "card-inserted" LED will both go out a few seconds after inserting a card.

Also, when I connect my camera to the same USB cable that I use for the card reader, the camera (memory card) will mount, but after ejecting it, I do not get the obligatory "remove ok."

I screwed something up. All connections are the same as before. The problem doesn't seem to be the USB port in the monitor: I plugged the card reader straight into a USB port on the Mac, and I don't get the usual "remove ok" there either after ejecting the card.

Connected to my Mac-mini (mid-2012 model) are also 2 hard drives, an optical drive, and a printer. Most peripherals go through a selfpowered USB hub (all peripherals have their own power spource). Keybord and headphones are also connected to the monitor USB ports. All those peripherals work.

What could I be overlooking? What should I check?

--
http://www.flickriver.com/photos/photography-by-thomas/