I've run into a problem upgrading from 1.4.3 to 1.4.4 or 1.4.5

With 1.4.4 and 1.4.5, I'm getting error messages like

[[59597,1],0] routed:binomial: Connection to lifeline [[59597,0],0] lost

The error does not occur if I restrict the host list to localhost.

Basic tests like 'mpirun hello_c' work properly.  The problem occurs using the R package Rmpi package.  (I've tried the R mailing lists, but so far to no avail.) This R package does work reliably with openmpi 1.4.3.

Could some one explain what an error message like this indicates? Is something timing out? Any idea what changed after 1.4.3 that might lead to this kind of problem?

FYI I'm running ompi under Debian 6.0.4 (squeeze).