In scouring the internet for a cause and solution I determined that there really is no single cause for this behavior and I couldn't find a solution. It also appears to be a comman issue. However I eventually determined that the cell formula below with functions built in caused Excel to crash when deleting a sheet by macro. I'm not sure why it occurred, must be my "ChangeDateFormat" function but if you run into the same situation, it might be worthwhile to look into your worksheet formulas that contain functions you've created.

I tried disabling calculation but that didn't work so I created code in vba that replaced the worksheet formula which solved the problem. 

 
 
=IF(OR((ISERR(ChangeDateFormat(Operational_Period_Begin_Date))),ISERR(ChangeDateFormat(Operational_Period_End_Date))), "MM/DD/YY HHMM - MM/DD/YY HHMM", ChangeDateFormat(Operational_Period_Begin_Date)& " " & Operational_Period_Begin_Time & " - " & ChangeDateFormat( Operational_Period_End_Date) & " " & Operational_Period_End_Time)
I hope this helps someone else should they run into the same problem.

Gary