Could you please write us, what you deleted from Registry?
Does your registry cleaner support backup?
At first sight into a call stack, seems, that VA is not the origin of the crash. It seems to be crashing in some Windows.Forms methods and AFAIK we don't use Windows.Forms at all in VA, so that could also describe, why reinstalling to previous VA version did not help.
I don't know if it will help, but System Restore could restore also registry settings, however I would try it as last option.
I tried to repro the problem by deleting HKEY_CURRENT_USER\\Software\\Whole Tomato\\Visual Assist X but it worked fine for (VA gave normal trial dialog where I re-entered license).