Virtaulmin 3.73 "Loading" Reseller Page crashes IE

After upgrade to 3.73 we are experiencing issues with the Reseller area in both FF & IE.

In FF there is a constant “Loading” image immediately below the “Select Virtual server” dropdown but otherwise FF is usable.

In IE as well as the “Loading” we get a Security information warning - Virtualmin is on SSL - whether you answer Yes or No IE then crashes.

Screenshots attached

Has anyone else experienced this issue. Can anyone advise what is supposed to be loading?