Interoperability problem with dselect and apt

[Dancer <dancer@zeor.simegen.com>]

I'm not sure if this is a dselect problem, or an apt problem or just a
difficulty from following the debian potato upgrade path.

dpkg version: 1.4.1.6
apt version: 0.3.11

Running dselect and selecting 'upgrade' yields:

[apt output...package lists loaded]..
Reading Package Lists... Done
Building Dependency Tree... Done
Merging Available information
E: Invalid operation dumpavail

update available list script returned error exit status 100.
Press RETURN to continue.

This broke quite some time back (for me), but I never actually got
around to posting a bug report about it. I've not shoved this into the
debian bug-tracking system, yet, since I'm not yet sure which package is
causing the problem. Both apt and dpkg have been upgraded several times
since this began.

I have six potato boxes on which this occurs. I have two more that work
correctly. Colour me confused. Happy to provide any extra information
that might be of use.

D