I did some more investigation of the horizontal lines and really could not figure out what is causing it. My guess is that the FTDI chip is not buffering the frame data but passing it straight to the PC and the data gets lost in this transfer.
My results:
Laptop 1 (win7) consistently shows them (one in 10-20 images).
Laptop 2 (win10) never does. This one has USB3 but the cam86 is USB2 so it should not make a difference, unless the problem is caused by the chipset/drivers itself.
The CPU load does not seem to affect anything.
Gilles, which operating system are you using with your Indi drivers? I didn't get a chance to try them out on my main PC (linux) yet, have to figure out how to use Indi first
Pat, which operating system were you using with your old computer (that was showing lines) and which one are you using now (computer not showing lines).