SandDisk UltraFit is disconnected after windows sleep mode

I tested the following configurations:

W8.1

 - Sleep mode: Works fine (no USB-Stick disconnection on awakening)

 -  Hibernate mode: Works fine

W 7SP1:

 - Sleep mode on USB 2.0 port: Works fine

 - Sleep mode on USB 3.0 port: Stick disconnects during awakening.

It is really annoying for me to find that out because one reason for buying a USB 3.0 stick ist the better performance.

I decide to use the USB 2.0 device for the future so that I have the option to set my Laptop into Sleep mode during transport.

If anyone will have an idea to fix my problem please post. I will be happy!

   Joerg