SODIMM Thermistor, Result Code: 3900-0626, temp=0C, min=10C, max=100C

I'm getting the following diagnostic failure on my Latitude C800 (1GHz, A23 BIOS):

SODIMM Thermistor - Sensor Range Test                      : Fail
  Result Code: 3900-0626
  Msg: Temperature sensor out of range, temp=0C, min=10C, max=100C

I reached this result after the following events:

• I recently started observing that Win2K chkdsk was finding and fixing bad attributes and cross-linked files on a regular basis.  The more I used the system, the more it found later.  Using some disk diag tools, I was able to find the affected files and, sure enough, I was losing some.  One of these incidents left the system unbootable, which I repaired using chkdsk from Win2K's recovery console.
• I ran chkdsk -r, and the disk portion of the disk diagnostics looking for bad blocks, and the 90/90 test, repeatedly, in case there was some intermittant failure in the disk.  It's checked out perfectly every time.  I also ran the full suite of diagnostics once and got no errors.
• Next, suspecting possible OS/driver problems, I backed up everything, and reinstalled Win2K from the recovery CD (a clean install with a new partition), and nothing else.  No change in symptoms; I still got chkdsk errors after copying a bunch of files around.
• I ran all of the diagnostics repeatedly.  Once I started doing that, I find that I get the above diagnostic failure a large percentage of the time, but not 100% of the time.  All of the other diagnostics, particularly memory, cache and disk, run repeatedly without error.

Does anyone have any further insight on this one?  For example, if this points to a specific piece of hardware, what is it, and what's its part number?

I've looked at other forum articles with similar diagnostic failures.  Most appear to be associated with a bad BIOS version (A19?), but it appears that we're long past that, and I believe they all reported "temp=255C" or such, not 0C.  One other forum article suggests it might be the CPU/heat sink, but it's not clear whether the solution was simply adding heat conducting paste or completely replacing the CPU/heat sink with new ones as well.  And simply based on the title of the failing diagnostic ("SODIMM Thermistor"), I would blindly guess that the problem was closer to memory (which checks out fine) than the CPU (but I don't have sufficient internal system knowledge on this system to know).  So I seem to be at a dead end without some further insight.