Greetings!
Firstly, I'm delighted by the changes introduced in the beta and very excited to see the new progress. With that, I thought I would report in on my findings after testing the bug I and others have encountered when creating new characters in the 3.70 beta.
On (Custom - Easy) and (Custom - Too Easy) modes, upon reaching the skill point buy page when creating a character a bug is triggered where the "exit character creation" pop-up appears whenever entering any key or clicking on any part of the page. The bug does not seem to appear on (Custom) creation mode. After testing 8 new characters, the bug appears to be triggered anytime you either:
1) Use up all of your improvement options points; the pop-up of "All Options Used" appears, but selecting 'Undo last and return' becomes a loop because any further clicking or entering of keys triggers the pop-up.
2) Reduce any skill to its maximum lowest value; triggers the problem as outlined above.
I hope this provides some useful insight if you have not already found the source of the problem!