AC3 audiofilters getting unregistered in XP

I use the audiofilters pack downloaded from to play AC3 tracks (I re-wrote the install script to skip Morgan Stream Switcher, as it is problematic in XP), and it works great, EXCEPT:

They get de-registered every so often (by what, I'm not sure), requiring me to reregister them when I play something that suddenly has no sound.

Has anyone seen this happen and maybe have an idea why?

Thanks!