Yeah same problem I been having in my BFS version kernel were if you try to undervolt it would cause the bootloop an wifi not to load as that were its stops in the boot process. GPS you could try changing the GPS server (Google that one) and then it case of leave to get a lock, mine works...
getting bad audio (screeching sound) when using headsets or the in-car bluetooth
happens trying to talk to people all you get is a screeching noise.
this is for the Desire HD
please find logcat attached