What is the purpose of that line that follows the cursor? I don't understand. Very annoying. I just installed this, and so far I like 8.5 better. When I start the program, I get a bunch of errors every time. It tells me that my midi isn't set up right. "IDS_Title_Warn_Midi_Ports Not found in Text Resource file", "Cannot Open ARX midi port", "Midi Devices aren't set up properly". I sit there, and wait a few minutes, and it seems to fix that stuff, but it does it every time I start the program? The Latency is much worse than with 8.5 Pro. I have to turn off all of the effects in other tracks, to reduce the latency on the one that I am recording (audio). I'm not impressed. I am glad I didn't waste money on X1, or X2. If anyone knows how to fix this stuff, I'd be happy to hear about it. Thanks

That line is Aim Assist. Press X to toggle it. 
 
I would go in to Preferences MIDI and make sure your system is set up right.  Also be sure to turn on your gear before you start Sonar. 

What you are experiencing is not even remotely normal. We need more details if you want to know how to fix stuff. I assume you installed Sonar with any virus scanners turned off, did the reset/rescan, and allow your computer to boot fully before starting Sonar. On my system sometimes it takes up to 30 seconds for the computer to recognize the interface and handshake with it. If I try to boot up Sonar before then, it won't find the interface and complaint that stuff is missing.

+1 to everything above.   The base DAW > Interface settings and preferences are the same as 8.5, so it should be a matter of figuring out how things are set differently between the two.    It's more the UI and certain workflows that have changed in X3 and that may require some adjustment -  and given a fair chance things can really fall into place.  There's a reason X3 (out of the "X" series) has become as popular and well liked as it is.