Negative time with ps

[Martti Kuparinen <martti.kuparinen%iki.fi@localhost>]

I'm getting weird output from domain0's ps command. Any ideas
what's causing this?

# uname -a
NetBSD xen 3.99.1 NetBSD 3.99.1 (XEN0) #0: Tue Mar 22 11:35:09 EET 2005 
 martti@localhost:/usr/src/sys/arch/i386/compile/XEN0 i386

# ps axw
PID TTY   STAT    TIME COMMAND
  0 ?     DKs  -18524836:-38.94 [swapper]
  1 ?     Ss   0:00.01 init
  2 ?     DK   0:00.00 [cryptoret]
  3 ?     DK   0:00.00 [atabus0]
  4 ?     DK   0:00.00 [atabus1]
  5 ?     DK   0:00.00 [usb0]
  6 ?     DK   0:00.00 [usbtask]
  7 ?     DK   0:00.00 [usb1]
  8 ?     DK   0:00.00 [pms0]
  9 ?     DK   0:00.00 [atapibus0]
 10 ?     DK   -18524836:-38.94 [pagedaemon]
 11 ?     DK   -18524836:-38.98 [ioflush]
 12 ?     DK   -18524836:-38.94 [aiodoned]
211 ?     Ss   0:00.02 /usr/sbin/syslogd -s
375 ?     Is   0:00.01 /usr/sbin/sshd
432 ?     Ss   0:00.03 sendmail: accepting connections
474 ?     Ss   0:00.01 /usr/sbin/cron
495 ?     Is   0:00.00 /usr/sbin/inetd -l
537 ?     Ss   0:00.14 sshd: root@ttyp0
542 ?     Ss   0:00.17 sshd: root@ttyp1
 77 ttyp0 Ss+  0:00.06 -bash
536 ttyp1 Ss   0:00.07 -bash
721 ttyp1 R+   0:00.01 ps axw
500 ttyE0 Is+  0:00.01 /usr/libexec/getty Pc ttyE0
501 ttyE1 Is+  0:00.01 /usr/libexec/getty Pc ttyE1
477 ttyE2 Is+  0:00.01 /usr/libexec/getty Pc ttyE2
494 ttyE3 Is+  0:00.01 /usr/libexec/getty Pc ttyE3