Hi there. I hear you, I've also found a number of painful bugs in recent releases. Can't move errors are sometimes related to grouped objects way out at the edge of the canvas. And yes, I've also found a bug where a non-interactible object (which I didn't make) is way out there at the edge of the canvas causing that error. It usually goes away when I restart AI though.
The most productive way through this, I've found, is as follows:
1) Check the Illustrator uservoice forums to see if someone else has identified steps to reproduce this bug. If so, vote. Now go to step 3. 2) If you can't find someone elses' steps to reproduce your bugs then you need to do this for yourself. This is annoying because it's QA work which you shouldn't have to do, but if you want this bug fixed, you need this. Now make your own bug report on UserVoice detailing the steps. 3) Now go chat to an Adobe support agent and take them through the steps to reproduce your bug, and also send them the link to your UserVoice bug.
And (based on my experience) your bug may well be fixed in a subsequent release... around 12 months later.