can burn cd's, can't read once burnt

[Timothy Smith]

i have an odd issue with 6.0 that i've been trying to solve for ages and 
nobody seems to know how to answer.

1. i can mount any cd's or dvd's THAT I DIDN'T BURN. makes no difference 
what media is used.

2. i burn a dvd like so

growisofs -dvd-compat -Z /dev/cd0=bailes.iso

outputs some info like this...

1608941568/1616412672 (99.5%) @3.9x, remaining 0:03 RBU 22.3%
builtin_dd: 789264*2KB out @ average 1.4x1385KBps
/dev/pass0: flushing cache
:-[ SYNCHRONOUS FLUSH CACHE failed with SK=3h/ASC=A0h/ACQ=80h]: 
Input/output error

and i find i have a dvd i can't mount on my machine, but under say 
windows i CAN mount it. the same thing applies to cdr's, although i 
don't get any error messages.

so i know my drive works, but it appears freebsd does not. as you can 
see by my dmesg below i have  cam loaded and working, i've also tried 
turning off dma in loader.conf with no success.

acd0: DVDR <HL-DT-ST DVDRAM GSA-4160B/A301> at ata1-master PIO4
ad10: 190782MB <Seagate ST3200822AS 3.01> at ata5-master PIO4
Trying to mount root from ufs:/dev/ad10s1a
cd0 at ata1 bus 0 target 0 lun 0
cd0: <HL-DT-ST DVDRAM GSA-4160B A301> Removable CD-ROM SCSI-0 device
cd0: 16.000MB/s transfers
cd0: Attempt to query device size failed: NOT READY, Medium not present