Hey, im not sure if the ringtone loop related to the frx06 build. I never noticed the ringtone not looping until i installed frx06. Heres the link to the xda thread that shows you how to make it loop. Im not sure if argghh is aware of this problem but according to the thread you just use a .ogg editor and add android loop code to it.
xda-developers - View Single Post - Fresh Froyo
this is the direct link to the forum that has you the link to the file that is already edited
Issue 2 - vogue-android - Ring tones only ring once - Android for the Vogue msm7500 (also works with some msm7200 series HTC GSM phones) - Google Project Hosting
i know its for a different phone, but i only used audio files that they supply with the loop code.
hope this helps you and/or someone else