temporary workaround, make the emitter static, and animate the armature, then just switch the emitter back to normal for render. for some reason, the armature only “locks” with a non-static emitter, but switching it to non static after animating seems to work.
if its not in the tracker you should probably report it.
this “locking” also happens when using an empty as a proxy, both with normal parenting and copy loc constraints.
This has come up numerous times. Mike reported it for 2.42 in the bugtracker last year, #4877. Not sure if it’s close to being fixed, but maybe this link is a start for you.
The whole particle system is being recoded, and will hopefully be in the next release (after 2.45), and I think this is solved there. You might check out a recent particles build at www.graphicall.org.