have your ruled this out as simply being a symbology issue? have you tried to float one of the rasters in the raster calculator prior to division to ensure floating point division? Have you investigated the histogram for the data?
The output looks correct to me--there's nothing anomalous about the range, because the denominator includes both negative and positive numbers.
Am I wrong in assuming the ranges of dividing both rasters should calculate as following because those two cells are being divided?
For example the two maximum raster values:
51.86/38.263 = 1.355356