particles not emitting from emitter!?

i’ve basically got a plane emitter that moves along the x axis while emitting particles. when i play the animation on the timeline for the first time the particles come from the moving emitter as expected. but when it loops to play through again, it always emits the particles from the starting position of the plane? baking/freeing bake doesn’t seem to help the issue.

i’m using 2.5 svn, so i was thinking it might be a caching bug, or it might be that that i need to do something specific to tell particles that an emitter is moving?

thanks so much for any help!