Have you tried updating everything related to the card reader to make sure it's not your issue?
I see lots of different variations of the C55D. But, when I look at updates for some of the models using a quick search, it looks like Toshiba has released a *LOT* of updates related to the Realtek Card reader most of the C55D series models appear to use.
For example, if you click on the drivers and updates tab from this page, then keep clicking on the "more" link at the bottom of the updates, you'll come to a "Realtek Card Reader" listing that you can click on.
When I click on that Realteck Card Reader listing, I see a that a lot
of different updates have been released for it (one every month or two).
This is a link to the most recent card reader update I see for for the C55D-A5208 model I'm looking at:
See the attached screen capture showing a number of others for a C55D-A5208 (and without your complete model info, I don't know if different updates may be available for your specific laptop).
But, as many updates as I see have been made available for the C55D Card Reader, I would not rule out that you need to update anything related to your card reader for starters.