preposterous TOD clock time on 5.0

Hi,

On my 735/125, kernel complains about TODR at boot as the following:
---
root file system type: ffs
WARNING: preposterous TOD clock time
WARNING: using filesystem time
WARNING: CHECK AND RESET THE DATE!
Enter pathname of shell or RETURN for /bin/sh: 
---

Today I've replaced a lithium battery in the machine
but it still complains. I also try TODR_DEBUG kernel and it says:

---
TODR-GET-SECS: rv = 0
TODR-GET-SECS: rtc_offset = 0
TODR-GET-SECS: 1970/05/09 03:46:21, (wday 6) (epoch 11072781.000000)
WARNING: preposterous TOD clock time
WARNING: using filesystem time
WARNING: CHECK AND RESET THE DATE!
---

Even after the TOD clock is updated proper as following:
---
unmounting file systems... done
TODR-SET-SECS: rv = 0
TODR-SET-SECS: rtc_offset = 0
TODR-SET-SECS: 2009/05/07 15:05:18, (wday 4) (epoch 1241708718.950679)
rebooting...
---

If I set date in Boot Administration mode on PROM
the kernel read TOD clock properly even after powercycle,
so it looks hp700/dev/pdc.c:pdcsettod() could mangle TOD clock.
(too large epoch?)

Is anyone else seeing this?
(note it's on 5.0 so time_t is still 32 bit)
---
Izumi Tsutsui