I've got music on an external hard drive which mounts happily. It also opens as a folder window though, which I don't want it to do. I'm sure there's a very simple preference to change this but the only ones I can find are to do with CDs etc.
Main Menu>System Tools>System Settings>System Section>Details>Removal Media
Check "Never prompt or start programs on media insertion"
No CD, no DVD, no usb stick, no media will start automatically, only will be mounted.
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)