Hi Mike,

I had similar problems a number of years ago when I bought the older style USB2 ASI120MM (It was cheap in a sale). I ended up taking it back to the shop and upgrading to the new version as I could not get it to work consistently. Since then I have had no problems.
The ASI software drivers work pretty well with KStars and I have never considered changing it as it just works. It has only ever been used as a guider in an OAG system. I was also keen to keep the brand consistent for compatibility as my main camera is also a ZWO.
My advice would be to cut your losses and get a USB3 version.