windows live mail does not always open in w/10

i have upgraded to w/10, and had wlm/2012 installed on 8.1 prior to the upgrade.  it works fine MOST of the time, but occasionally i get the screen that says wlm is starting, and nothing happens.  the little circle keeps spinning, but the program never opens.  i can't seem to stop it any way but forcing a power down.  most of the time it will start/open after a power down/reset, but not always.  btw - i do have an internet connection when this failure happens.