Blu Ray burner issues with Toast

I am trying to hook up a Pioneer BDR-206 to my iMac so I can burn HD movies to Blu Ray. I'm new to Mac so pretty much everything I do is a learning process. I used iMovie to edit the AVCHD files and then exported them. I am using Toast 11 Titanium to burn the movies. Toast seems to encode the movies just fine. But when it starts to burn them I get a hardware error and Toast crashes. I have tried changing the burn speed and made sure the buffer underrun was checked. It crashes at different intervals. I even was able to get one of the Toast discs to completely finish but then the disc wouldn't play in my Blu Ray player. The menu showed up but the videos wouldn't load. I have tried all of Toasts support suggestions but none of it works. I'm hoping someone out there knows more than the tecs at Toast. Otherwise, I'm toast. I've wasted about $25.00 in blank Blu Ray discs already. The error code i get is:

The drive reported an error: Sense Key=Hardware error Sense Code= 0x08, 0x01 Logical Unit Communication Time out

I forgot to mention that I am using the BDR-206 in an enclosure with USB2 connection to iMac. The iMac is new with the iCore5 processor.