Seems that a dependency of the .XLL file might be missing as per the URL below,
https://social.technet.microsoft.com/Forums/office/en-US/533b124a-88e3-4877-9318-1c22fb7cf415/excel-2013-tries-to-open-rsexcelxll-at-every-beginning?forum=excel
See if that gives you a direction to troubleshoot.