Dough1967 - I too play guitar and have had problems with numbness. There have been two changes that have corrected the issue. One was to raise my bars a bit. I still have some drop, 5cm or so, but nothing crazy like the pros. The second step was to level my saddle, a Fizik Arione. Now I have no problems. I can even ride without gloves without discomfort or numbness. Another thing to check is the fore/aft position of the saddle as this can affect your weight distribution. You should be able to take your hands off the bars and support your weight with your core muscles (abs, sides and lower back). The good news is the numbness will go away and your hand should be normal again once the fit issues are corrected.

http://www.peterwhitecycles.com/fitting.htm - check the section on fore/aft positioning.