Hang on boot - "ATAPI_RESET no interrupt" with DVD+RW

Since last night and continuing today, the kernel from -CURRENT usually 
hangs during boot.  Safe mode worked once, but the second time it didn't 
work.  I now got in through single-user mode, so it appears to just work 
every once in a while, randomly.

I have a dmesg from the booted system below.  When it hangs, it stops 
one line after "ata1-slave: FAILURE - ATAPI_RESET no interrupt", in 
other words it hangs after detecting ata1-master but before detecting 
ata1-slave, my DVD+RW drive.

Copyright (c) 1992-2004 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 5.2-CURRENT #2: Tue Jul 13 10:45:43 PDT 2004
    brian_at_brian:/usr/obj/usr/src/sys/MYKERN
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: AMD Athlon(tm) XP 1800+ (1533.40-MHz 686-class CPU)
  Origin = "AuthenticAMD"  Id = 0x662  Stepping = 2
  
Features=0x383fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
  AMD Features=0xc0480000<MP,AMIE,DSP,3DNow!>
real memory  = 1073676288 (1023 MB)
avail memory = 1045405696 (996 MB)
ACPI APIC Table: <AMIINT VIA_K7  >
ioapic0 <Version 0.3> irqs 0-23 on motherboard
acpi0: <AMIINT VIA_K7> on motherboard
acpi0: [GIANT-LOCKED]
acpi0: Power Button (fixed)
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x808-0x80b on acpi0
cpu0: <ACPI CPU> on acpi0
acpi_button0: <Power Button> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
agp0: <VIA Generic host to PCI bridge> mem 0xe0000000-0xefffffff at 
device 0.0 on pci0
pcib1: <PCI-PCI bridge> at device 1.0 on pci0
pci1: <PCI bus> on pcib1
pci1: <display, VGA> at device 0.0 (no driver attached)
dc0: <LC82C115 PNIC II 10/100BaseTX> port 0xe800-0xe8ff mem 
0xdfffff00-0xdfffffff irq 17 at device 6.0 on pci0
miibus0: <MII bus> on dc0
dcphy0: <Intel 21143 NWAY media interface> on miibus0
dcphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
dc0: Ethernet address: 00:a0:cc:33:8e:1b
dc0: [GIANT-LOCKED]
pcm0: <Creative EMU10K1> port 0xe400-0xe41f irq 17 at device 10.0 on pci0
pcm0: <Cirrus Logic CS4297A AC97 Codec>
uhci0: <VIA 83C572 USB controller> port 0xd800-0xd81f irq 21 at device 
16.0 on pci0
uhci0: [GIANT-LOCKED]
usb0: <VIA 83C572 USB controller> on uhci0
usb0: USB revision 1.0
uhub0: VIA UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
uhci1: <VIA 83C572 USB controller> port 0xdc00-0xdc1f irq 21 at device 
16.1 on pci0
uhci1: [GIANT-LOCKED]
usb1: <VIA 83C572 USB controller> on uhci1
usb1: USB revision 1.0
uhub1: VIA UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub1: 2 ports with 2 removable, self powered
uhci2: <VIA 83C572 USB controller> port 0xe000-0xe01f irq 21 at device 
16.2 on pci0
uhci2: [GIANT-LOCKED]
usb2: <VIA 83C572 USB controller> on uhci2
usb2: USB revision 1.0
uhub2: VIA UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub2: 2 ports with 2 removable, self powered
ums0: Logitech USB-PS/2 Optical Mouse, rev 2.00/11.10, addr 2, iclass 3/1
ums0: 3 buttons and Z dir.
pci0: <serial bus, USB> at device 16.3 (no driver attached)
isab0: <PCI-ISA bridge> at device 17.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <VIA 8235 UDMA133 controller> port 
0xfc00-0xfc0f,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 17.1 on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
acpi_button1: <Sleep Button> on acpi0
fdc0: I/O to control range incorrect
sio0 port 0x3f8-0x3ff irq 4 on acpi0
sio0: type 16550A
sio1 port 0x2f8-0x2ff irq 3 on acpi0
sio1: type 16550A
ppc0 port 0x378-0x37f irq 7 on acpi0
ppc0: Generic chipset (EPP/NIBBLE) in COMPATIBLE mode
ppbus0: <Parallel port bus> on ppc0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
atkbdc0: <Keyboard controller (i8042)> port 0x64,0x60 irq 1 on acpi0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
fdc0: I/O to control range incorrect
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
orm0: <ISA Option ROM> at iomem 0xc0000-0xce7ff on isa0
pmtimer0 on isa0
fdc0: <Enhanced floppy controller (i82077, NE72065 or clone)> at port 
0x3f7,0x3f0-0x3f5 irq 6 drq 2 on isa0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
Timecounter "TSC" frequency 1533400741 Hz quality 800
Timecounters tick every 10.000 msec
acpi_cpu: throttling enabled, 16 steps (100% to 6.2%), currently 100.0%
ad0: 114473MB <WDC WD1200JB-00CRA0> [232581/16/63] at ata0-master UDMA100
ad1: 114473MB <WDC WD1200JB-00CRA1> [232581/16/63] at ata0-slave UDMA100
ata1-slave: FAILURE - ATAPI_RESET no interrupt
ad2: 78533MB <IC35L080AVVA07-0> [159560/16/63] at ata1-master UDMA100
acd0: CDRW <TDK DVDRW420N> at ata1-slave UDMA33
Mounting root from ufs:/dev/ad0s1a