Why Does API:Sleep Work in this Case??

I run Excel from my VB6 Application using "CreateObject"
If I close Excel directly (Not from the VB6 App) and then
try to Start Excel from my VB6 app I get "Application Defined Error"
even though I execute oXL.Quit and set All object references "= Nothing"
prior to restarting Excel.

HOWEVER, if I allow the VB6 App to Sleep using API:Sleep AFTER
oXL.Quit and setting All Object references "= Nothing"
Excel again works as designed with NO errors.