error - isFinite(outDistanceForSort) -- persistent from old version of Unity?

I have a project that I've just updated from Unity3.5 to current (4.3.4), and I'm encountering the isFinite() error pop up intermittently. It seems to happen most often when I'm destroying objects that have particle systems, but it isn't consistent.

I would just ignore the errors (they only happen occasionally), except that the system chugs noticeably for a moment.

I've searched for this error, and I've found references to it being a bug in older versions of unity. Is it possible that it has somehow persisted into unity 4.3.4 in this case because it was an old project? The only other time I've encountered this error is when I've been doing custom particle effects and I accidentally assign particles values too large for unity to track.

Are there any other reasons I might be getting this error? I'm hoping to avoid having to create an entirely new project and port all of the assets and rebuild the whole project :/

reference profiler pics:

this is paused on the frame where error is occurring. it actually appears that the chug in performance is due to the stack trace and error logging, not necessarily the error itself... at least as far as I can tell

this is an overview of activity during the time. performance is just fine except for these intermittent spikes.