[VPAstro (Andrew and Cam)]

Hi All, Hoping someone may be able to help.
I have been autoguiding for years using a Meade dsi ii and an Orion st80 using a GPUSB and PHD2. My imaging scope is and ED80 on a HEQ5 and I use a polemaster for polar alignment.
I have been able to do 10min subs without any trailing using this setup and my PHD graph is usually pretty stable.
I switched my guide cam to an Orion SS autoguider last night, connecting it directly to the st4 port and had major issues. The phd graph was all over the place alternating in both RA and Dec making corrections of sometimes greater than 3". I thought maybe it was something to do with the ST4 port on the guider, so I reconnected the GPUSB, and got the same result. I was getting trailed stars on one minute subs. After struggling with this for a few hours, I decided to go back to the Meade DSI II and PHD went back to normal operation with. Just wondering if anyone has experienced this before, or know of settings in PHD that be causing this behavior.
Thanks
Andrew...