The system crash when the system is under load and I printing stuff with 
my USB printer. Here I provide some crash information. I got a 2Gig 
kernelcoredump and a netbsd kernel with debugsymbols for it, so I can do 
some more digging if I get some hints on where to look.

the code is from anoncvs with netbsd-3 tag around 12 of may.

CVS Revisions of relevant files:
dev/usb/ohci.c  r1.157
dev/usb/usb.c   r1.81

My system:
NetBSD ngong.utopiafoundation.org 3.0_BETA NetBSD 3.0_BETA (NGONG) #2: 
Thu May 12 18:37:46 CEST 2005 
karl@ngong.utopiafoundation.org:/usr/src/sys/arch/i386/compile/NGONG i386

backtrace:
(gdb) bt
#0  0xc0b68000 in ?? ()
#1  0xc0578ef3 in cpu_reboot (howto=256, bootstr=0x0)
     at ../../../../arch/i386/i386/machdep.c:751
#2  0xc04affc3 in panic (fmt=0xc084bafe "trap")
     at ../../../../kern/subr_prf.c:242
#3  0xc0589344 in trap (frame=0xcd6a7e84)
     at ../../../../arch/i386/i386/trap.c:296
#4  0xc0102d07 in calltrap ()
#5  0xc034be05 in ohci_abort_xfer (xfer=0xc2af8580, status=USBD_TIMEOUT)
     at ../../../../dev/usb/ohci.c:2235
#6  0xc034b831 in ohci_timeout_task (addr=0xc2af8580)
     at ../../../../dev/usb/ohci.c:1888
#7  0xc076ee5f in usb_task_thread (arg=0xccd6b18c)
     at ../../../../dev/usb/usb.c:366

console at crash (from msgbuf in gdb):
uhidev1: Logitech HID compliant keyboard, rev 1.10/1.80, addr 3, iclass 3/0
uhidev1: 2 report ids
uhid0 at uhidev1 reportid 1: input=2, output=0, feature=0
uhid1 at uhidev1 reportid 2: input=1, output=0, feature=0
uhidev2 at uhub3 port 3 configuration 1 interface 0
uhidev2: Logitech USB Mouse, rev 1.10/6.20, addr 4, iclass 3/1
ums0 at uhidev2: 3 buttons and Z dir.
wsmouse0 at ums0 mux 0
<4>set{u,g}id pid 988 (netstat) was invoked by uid 1000 ppid 603 
(firefox-bin) w
ith fd 0 closed
ulpt0: at uhub0 port 1 (addr 2) disconnected
ulpt0 detached
ulpt0 at uhub0 port 3 configuration 1 interface 0
ulpt0: Brother Industries product 0x001a, rev 1.00/1.00, addr 2, iclass 7/1
ulpt0: using bi-directional mode
<5>ulpt0: offline
<5>ulpt0: offline
uvm_fault(0xc0a25920, 0, 0, 1) -> 0xe
fatal page fault in supervisor mode
trap type 6 code 0 eip c0770a5c cs 8 eflags 10286 cr2 48 ilevel 5
panic: trap
syncing disks... 11 11 11 11 11 11 11 11 11 10 9 9 9 9 9 9 9 9 9 9 9 9 
giving up

dumping to dev 0,6 offset 4067333
dump 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 
2001 2000

- Karl