Can't eject mounted discs (not the normal case)

[kthekuo]

First of all, this is not one of those the file inside the mounted disc is open resulting a failure in ejecting. This happened a few weeks ago, I can't eject the disc by just normally dragging it to the trash or right click on the icon and click "eject".
The only way I can eject the disc is through disk utility's "eject".

Does anyone know what causes this and the resolution for it?

 

[simsaladimbamba]

USB or Firewire disk or a disk inside the optical disk drive (ODD)?
Have you tried an SMC reset yet?
Intel-based Macs: Resetting the System Management Controller (SMC)

 

[kthekuo]

its just USB. Also, I can't seem to unmount DMGs either!...