I have a fresh install of Windows 8 at work.
I installed ArtRage 4.0.4
No Wacom Tablet, and no tablet drivers installed. (I'll have one soon.)

If Use Realtime Stylus is checked (and it is by default) the cursor and line freeze if I hold down CTRL to draw a straight line. When I release CTRL they go back to normal.

If I uncheck it and restart ArtRage it works fine.