Freeze isnt a tidy up command most people use it for. ITs something FAAR more fundamental than that. Indeed uncatious use of freeze can bbe a bad thing.
What freezing does i it makes the transformation matrix singular, and in the case of a light that does not have a underlying local transformation this would essentialy mean to move it to 0 0 0...
You coulg group the light undera a grouy thats at 0 0 0 tough.