panic upon starting X in recent -CURRENTs (intel driver)

Hi. After recent upgrade (from 21 dec to today's src) the kernel crashes 
when starting X with

panic: pmap_remove_all: page 0xc56e07f8 is fictitious

This is an i386 box (DELL Optiplex 745) with GENERIC kernel.
Using the latest X port with the 'intel' video driver.

Relevant portions of stack trace:

#9  0xc076874c in panic (
     fmt=0xc0b3958f "pmap_remove_all: page %p is fictitious")
     at /usr/src/sys/kern/kern_shutdown.c:555
#10 0xc0a73d52 in pmap_remove_all (m=0xc56e07f8)
     at /usr/src/sys/i386/i386/pmap.c:2125
#11 0xc097e8d9 in vm_object_page_remove (object=0xc56fbb00, start=916992,
     end=917120, clean_only=0) at /usr/src/sys/vm/vm_object.c:1887
#12 0xc09782b1 in vm_map_delete (map=0xc565a570, start=678580224,
     end=679104512) at /usr/src/sys/vm/vm_map.c:2307
#13 0xc097c1d4 in munmap (td=0xc5398660, uap=0xe79e0cfc)
     at /usr/src/sys/vm/vm_mmap.c:603
#14 0xc0a77cf3 in syscall (frame=0xe79e0d38)
     at /usr/src/sys/i386/i386/trap.c:1034

I still have the vmcore if someone wants to dig further.

Cheers
Michiel