When you have only one partition on the HD, it should be primary and never extended. So the problem.
How to solve this;
1- Backup your documents (photos, videos, etc)
2- Using LM LiveDVD, gparted, delete all partitions
3- Make 4 new partitions:
-sda1 Linuxmint files, 15GB ext4, /
-sda2 your files, 47GB, ext4, /home
-sda3 Linuxswap, 2 GB
-sda4, 10GB, ext4
sda4 is for test another distros.
LM16 Cinnamon (PC); LM14 Cinnamon with AMD Catalyst (notebook)
HP Pavilion g4-1316br, AMD Quad Core, 1,5 GHz, Radeon 6520G/7450M,
Linuxcounter Registered User #506065 (2008)