virtualbox.org

I have succefully installed Windows 7 on my imac.
The only problem is that windows does not recognize the Pioneer DVD RW drive in the imac - instead it has it as just a read-only cd drive.
I have tried the device troubleshooter within windows and virtualbox recognizes the Pioneer drive. This means I can't burn any CD's or DVD's
Any ideas how to fix this?

Enable Passthrough => see Manual.

Right done that but now it starts to burn a CD in Windows or Nero but it crashes after a few seconds - any ideas?

No. May work or not.

Its always better to burn on the host.

If its possible try to create iso i mages in the guest and burn them on the host.