Problem with pdbstr in the x64 build?

I’m seeing a problem where ssindex from the 6.6.0007.5
drop fails silently unless run with -debug:8 (well,
I didn’t try any small numbers.)

At -debug:8, I get the following error displayed:

ssindex.cmd [INFO] : … error writing C:.…\index192D4.stream
to E:.…\UnitTestUD.pdb (error 0xc1 loading mspdb60.dll)

Further investigation yields that the following command:

pdbstr -w -s:srcsvr -p:mypdb.pdb -i:walk.cmd

fails with the message “error 0xc1 loading mspdb60.dll”
if I run it from the x64 install directory, but works
if run from the x86 directory.

Is anyone else seeing this, or did I manage to mess
this up (perhaps by installing the x64 version and
then the x86 version?)

Thanks,

Joseph

PS. Note that mspdb60.dll is on my machine in the visual
studio install directory and in the 3790.1830 ddk, but
that the wdk only includes mspdb80.dll.