Hi Larry, I have a Cannon HG20 and normally do not have any trouble editing my AVCHD files. I record at 1920x1080i with a bit rate of 24 Mb/s and have no issues. However, I do have a quad core computer which makes things much easier. If you are only using a dual core computer then you have have problems. One thing I should mention is that encoding into the MPEG4 format does introduce some quality loss. I normally encode at 25 Mb/s MPEG2 and get good results. Cyberlink is aware of the MPEG4 encoding problems.
Sometimes PD will become unstable when working with AVCHD files. To fix this I reboot my computer and make sure the hard drive is degramented.
Q9300 2.5 GHz
4 GB Ram
Nvidia 9800 GT