Kernel panic on FreeBSD 10.0-CURRENT amd64

I have recently installed 9.1 and attempted to upgrade to 10.0-CURRENT
yesterday (largely in an effort to test the new radeon DRM code).
Unfortunately, upon rebooting, I am left at kernel debugger prompt:

cd0 at ata0 bus 0 scbus0 target 1 lun 0
cd0: <TSSTcorp CD-ROM  TS-H192C DE00> Removable CD-ROM SCSI-0 device
cd0: 33.300MB/s transfers (UDMA2, ATAPI 12bytes, PIO 65534bytes)
cd0: Attempt to query device size failed: NOT READY, Medium not
present - tray closed
panic: g_read_data(): invalid length 0
cpuid = 0
KDB: enter: panic
[ thread pid 13 tid 100014 ]
Stopped at      kdb_enter+0x3e: movq    $0,kdb_why
db> bt
Tracing pid 13 tid 100014 td 0xfffffe0002957490
kdb_enter() at kdb_enter+0x3e/frame 0xffffff800026a960
vpanic() at vpanic+0x147/frame 0xffffff800026a9a0
kassert_panic() at kassert_panic+0x136/frame 0xffffff800026aa10
g_read_data() at g_read_data+0x45/frame 0xffffff800026aa50
g_label_ntfs_taste() at g_label_ntfs_taste+0xde/frame 0xffffff800026aa90
g_label_taste() at g_label_taste+0x37b/frame 0xffffff800026ab60
g_new_provider_event() at g_new_provider_event+0xda/frame 0xffffff800026ab80
g_run_events() at g_run_events+0x167/frame 0xffffff800026abb0
fork_exit() at fork_exit+0x84/frame 0xffffff800026abf0
fork_trampoline() at fork_trampoline+0xe/frame 0xffffff800026abf0
--- trap 0, rip = 0, rsp = 0xffffff800026acb0, rbp = 0 ---

I'm no expert, but it appears to be  related to the NTFS partition I
have on a separate hard drive.

Any ideas what the problem might be or how to debug this further?

Adam