geometry error

[Landartma]

I had a file which kept seizing up with the blue wheel of death but not crashing it was trying to solve something related to geometry.  The first time I went through all my layers and found some stake objects and other stuff that went awry. Then I took all the layers cut and pasted in place on a new drawing file and I was off to the races.  That file is working fine.  I just solved the same issue with another file.  I think. What causes that to happen?  What's the most efficient way to find problems so they can be fixed. 

[P Retondo]

Remove half the objects in the file, and test. If everything is fine, then the problem is in the half you removed. If you still have a problem, it’s in the half you didn’t remove. Take the half which has the problem, cut another half out of it. Test. Repeat until you get down to a few objects. This process takes about 10 to 15 minutes.

[Landartma]

Yes I have done that.  The problem seems to exist in the items in my None class.  I think I may have narrowed it down to a tile pattern I made.  But now I want to know what causes the issue I'm having.  Mostly so I don't repeat it.  I will post it once I narrow it down.