Hi Nigel,
I use heaps of HS-65's of both types with 6008 and 6106 receivers which have a high speed mode, as well as 608 and 617 receivers which don't. The only problem I've ever had is the obvious one where I set the high speed mode inadvertantly.
I'm sorry to hear you are having problems! I just wanted you to be aware that it isn't a universal issue, you just happen to be the lucky one
Go Great!
Ken.