This is from the victor reader stream faq:
Q. Do I always need to use the Windows Safely Remove option to disconnect my 
Stream
or remove my SD card from my card reader?
A.
It depends on your computer. Windows recommends that you use the Safely 
Remove option
when write-caching is enabled for the USB device. If write-caching is not 
enabled
then the device is said to be optimized for quick removal and the Safely 
Remove option
is not needed. The Safely Remove option is intended to prevent the SD card 
from becoming
corrupted when write-caching is enabled. To be safe, the Stream 
documentation always
recommends using the Safely Remove option. You can check and/or modify your 
computer’s
setting for write-caching. First connect the Stream or put a card into your 
SD card
reader. Then open the Control Panel, select System, then open the device 
manager
in the Hardware tab. Then look for your USB device on the list of disk 
drives. View
the Properties of your USB card reader and check the Policies tab to see if 
the device
is enabled for write-caching. The information in the Policies window 
explains the
relationship between write-caching and the Safely Remove option. If you do 
not wish
to worry about such technical issues then always using the Safely Remove 
option before
disconnecting your Stream or removing the SD card from your USB card reader 
is recommended.