the program stops working whenver div command is executed

Question

lea   ecx,wtavg
push  ecx
call  StdOut
xor   eax,eax
lea   eax,wtsum     ; I have values stored in these variables(integer data)
mov   eax,[eax]
lea   ecx,sumwts
mov   ecx,[ecx]
div   ebx           ; The problem lies here, "Windows Stopped working" 
lea   edi,temp1
mov   [edi],ebx
lea   edi,rem
mov   [edi],edx
print ustr$(eax),0,0
lea   eax,pt
push  eax
call  StdOut
lea   eax,rem
mov   eax,[eax]
mov   edx,100
mul   edx
lea   ebx,temp1
mov   ebx,[ebx]
div   ebx
xchg  ebx,eax
print ustr$(ebx),13,10
lea   eax, prompt
push  eax
call  StdOut
mov   eax,100
push  eax
lea   eax,temp1
push  eax
call  StdIn
call  ExitProcess

Answer 1

I don't see anywhere where you've actually set ebx to something before attempting to divide by it.

It's unlikely to end well if ebx is set to zero at that point since Documentation for the div instruction indicates that an exception is raised for that situation:

if (Source == 0) Exception (DE); // divide error

If you're trying to divide something by sumwts, you should probably load that into ebx or use ecx as part of the div instruction:

lea  ecx,sumwts
mov  ebx,[ecx]        ; Or leave as mov ecx,[ecx]
div  ebx              ;   then use div ecx.

You may also want to ensure that edx has been set to zero somewhere before the div, since that's used in the division as well. For div ebx, the actions are effectively:

tmp <- edx:eax
eax <- tmp / ebx, exception if eax would overflow
edx <- tmp % ebx