it seems there is an issue with the cardreader unit, rather than a salix problem.
I need to find out about the cardreader and the various slots and their design and function.
Maybe its a design feature...
I apologize for my broken English ! May be you could format your usb key in ext3 and try to read/write on it on Linux just to be sure that your key is ok.
If no issue happens, format your key with Windows in fat32 and read/write on it on Linux.
It seems to me there wouldn't be any problem.
Best regards.