Removable disks appear on booting Windows when you have a internal multi card reader. They appear in "Disk Management" (diskmgmt.msc) and in "My Computer". If there are no cards in them (which in mostly is) these drives do not open. You can't do anything with them. They just lie there. Its a nuisance to me.
The following steps describe way to prevent that from happening.
1. Open "Device Manager" (Run devmgmt.msc). With the drives appearing it should look like this
2. Right click on "Universal Serial Bus controllers->USB Mass Storage Device" and click "Disable". You should get a pop-up message like this.
Your "Device Manager" should look like this now