This seems to be hardware problem - I have the same thing happening on my U9200. The reader performed OK when the laptop was new, then began to exhibit this behavior around the end of the warranty period (of course...
First you should try cleaning the contacts on the card and maybe blow some air into the reader. That didn't help in my case so I played with the card until I found a position in which it stayed connected, which meant pushing the card towards its right side while inserting it in the reader and pushing it by the lower left corner.
I'm fairly convinced that one of the contacts inside got pushed backwards by a different card or something, but I can't do much about it since the reader can't be opened up without soldering