I just used Paragon Partition Manager Free Edition 2014 on my Windows 8 to transfer space from one of my Windows logical partition to my Ubuntu Linux partition (I have only one partition for Ubuntu). After the operation, the software gave me a message: "If you have Linux installed, please reinit its boot loader". I do not know how I am supposed to reinit its boot loader or what exactly a boot loader is (besides Grub). So, what do I do before I reboot my computer. I am not fond of broken loading screens.