Hi

From experience this is usually caused by a bad disc - a very common problem if using economy discs.

What make and type of BD discs are you using?

Is this happening with every disc you try?

I would recommend using good quality BD-RE (rewriteable) discs for the initial burn, quite often you will find that you need to go back and change something which was missed on the computer monitor however is noticeable on the big screen. and can then re-use the BD-RE disc

Once you have the finalised version on the BD-RE and it is tested OK, this can then be copied using a burning program eg Nero, ImgBurn etc to a standard BD disc and the BD-RE disc recycled for the next project.

The net effect is this saves you money in the long run and finding a use for the 'coasters'.

HTH

John EB