Will Acronis allow you to slow the burner down. I would say the burner is the problem. have you tried mounting the image in explorer, right click the image file and choose explorer, it should mount as another drive so you can examine the files folders. when you have done with the above right click the drive and choose unplug
If Acronis True Image ceases running or produces errors, its files might be corrupted. To fix it, you will have to recover the program. To do this, run the installer again. It will detect Acronis True Image on your PC and will ask you if you want to recover (update) or remove it. Click Recover and click Proceed.
Are you creating your images in the "Acronis Secure Zone" or just directly onto your second hard drive? By using the "Secure Zone" your images cannot be affected by any Windows applications. Its easy to set up, just have a look in the Help file.It says you can set it up on one drive only so, in your case, you would set it up on your second drive.
Also, and I don't know if this actually makes a difference, I defragment the drive before creating an image of it.