This bug has been opened here: https://bugzilla.ubuntu.com/8129

"When choosing maximum possible for write speed while tyring to burn a data cd,
nautilus ejects cd saying that my system is too slow for writing at that speed.
I can burn cd fine if I choose 8x speed. There wasn't this issue in Warty.

I'm using Hoary preview release with daily updates. My laptop is Sony PCG-GRX500.
...
I set the debug gconf key and tried to burn again at max speed. Following is the
Disc writing error details:

cdrecord: fifo was 0 times empty and 1 times full, min fill was 0%.
cdrecord: fifo had 64 puts and 0 gets.
cdrecord: Try to use 'driveropts=burnfree'.
cdrecord: Max DMA data speed is 11.
cdrecord: DMA speed too slow (OK for 11x). Cannot write at speed 16x.
cdrecord: WARNING: This causes a high risk for buffer underruns.
cdrecord: Permission denied. WARNING: Cannot set priority using setpriority().
cdrecord: Operation not permitted. WARNING: Cannot set RR-scheduler
SCSI buffer size: 64512
cdrecord: Warning: using unofficial version of libscg (ubuntu-0.8ubuntu1
'@(#)scsitransp.c	1.91 04/06/17 Copyright 1988,1995,2000-2004 J. Schilling').
Linux sg driver version: 3.5.27
Warning: Open by 'devname' is unintentional and not supported.
scsibus: -2 target: -2 lun: -2
devname: '/dev/hdc'
scsidev: '/dev/hdc'
cdrecord: WARNING: This causes a high risk for buffer underruns.
cdrecord: Permission denied. WARNING: Cannot set priority using setpriority().
cdrecord: Operation not permitted. WARNING: Cannot set RR-scheduler
cdrecord: If you have unexpected problems, please try Linux-2.4 or Solaris.
cdrecord: There are unsettled issues with Linux-2.5 and newer.
cdrecord: Warning: Running on Linux-2.6.10-5-686
cdrecord: Continuing in 5 seconds...
cdrecord: Future versions of cdrecord may have different drive dependent defaults.
cdrecord: Asuming -tao mode.
cdrecord: No write mode specified."