You indicate there is no option to do this in the registry editor.
Click your Start Button, type regedit and hit Enter to open the Registry Editor
Click View and make sure 'Address Bar' is turned on
Paste this into the Address Bar at the top and hit Enter
HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics
In the right hand pane, what values are set for IconSpacing and VerticalIconSpacing
By default, those values should be this minus value: -1128
Please provide a screenshot of that registry editor window.