.how to change the grub settings...or master boot record setting...
When you installed suse the grub root was /dev/sdb (or anything from your external volume) so the grub system image is in that disk, not in your internal hard disk currently occupied by windows. Each time the volume is detached the grub on the mbr cannot find its root records, the booting can fail.
There are many ways of solving your challenge. This one small solution.--
In your internal hard drive (if space permits, anywhere, primary or logical partition) create at least 100MB partition, mount it as your suse's "/boot" directory. Reinstall grub or just run setup or grub-mkconfig -o /boot/grub/grub.cfg then run 'update-grub'. Reboot without your external drive and grub will point you everything including chainloading your windows.
Hope that helps. Good luck.