I was having more or less the same problem. A few times I could hear the music from the computer, but every time I paused the music it was hard to get it working again.
This is what I did, and it seems to be working:
1) Delete the DS980 headset as bluetooth device.
2) Reset the headset following the instructions on the manual (1. On/Off key for 5 seconds and then 2. Press and hold the On/Off key and the call handling key simultaneously for 5 seconds.)
3) Pair the headset again with the computer, but this time I only selected the headphones service (and uncheck the headset service).
4) After that I click on the Bluetooth Status on the Menu Bar, and then go to HBH-DS980, and select "use headphones". (I think this is the important part, but before resetting the headset this didn't work all the times)
And now I can hear the music and other sounds from the computer. I hope this helps.
I think next time I may get the iSkin Cerulean F1 + TX.