Error with this program?

[userct]

I'm having trouble finding where I am going wrong with this program which checks for perfect numbers.
Here are my errors:

I ran it but it's giving me an error saying
Exception occurred at PC=0x00000000
Bad address in text read: 0x00000000
Attempt to execute non-instruction at 0x80000180

## Registers:
## $s3 Holds the number 1
## $s1: Hold the Sum
## $v2: Counter (May not be used)
## $t3: Integer divided by 2
## $t4: Remainder
## $t5: Divisor
## $t6: Temporary check if less than 1

.text
.globl main

main:
        li      $s3, 1      # Load register $s3 with 1

start:

        li      $t5, 1      # Set the divisor to zero
        li      $s1, 0      # Load the Sum to zero
        li      $t3, 0      # Integer divided by two set to 0
        li      $t6, 0      # Temporary check if less than 1

        li      $t0,4       # access prompt
        la      $a0,prompt  # print prompt
        syscall


        li      $v0,5       # code 5 == read integer
        syscall             # Invoke the operating system.

        divu    $t3, $a0, 2 # Put the integer divided by 2 in $v3

    #BELOW CODE CHECKS IF INTEGER IS <1 and ENDS IF IT IS        
        sltu  $t6,$a0,$s3   #  if ( $a0 < $s3 ) (Int < 1)
                            #    $t6 = 1
                            #  else
                            #    $t6 = 0
        beq   $t6,$s3,end

    # THIS IS THE END OF CHECKING IF INTEGER < 1 

    # BELOW WILL DETERMINE IF THE INTEGER IS PERFECT

run: 


         remu $t4,$a0,$t5     # divide $a0 by $v5. Put the
                              # remainder in $v4. Operands are
                              # unsigned.



        beqz  $t4,addSum      # If the remainder is equal to zero
        b     check



addSum: 
        addu $s1, $s1, $t5     # Add the divisor to the Sum

check:
        ble  $t5, $t3, determine # If register 3 is less than integer/2

        addiu $t5, $t5, 1    # Increment the divisor by 1

        j run


    # END OF DETERMINING IF INTERGER IS PERFECT

determine:

        beq     $s1, $a0,perfectPrint
        b       notPerfectPrint

perfectPrint:       

        li      $v0,4       # code 4 == print perfect
        la      $a0,perfect # $a0 == address of the string
        syscall             # Invoke the exception handler.

        j start             # JUMP TO THE START OF THE PROGRAM

notPerfectPrint:

        li      $v0,4       # code 4 == print string
        la      $a1,notper  # $a1 == address of the not perfect
        syscall             # Invoke the exception handler.


        j start             # JUMP TO THE START OF THE PROGRAM


end:
        li      $v0,10      # code 10 == exit
        syscall             # Halt the program.


         .data
perfect: .asciiz  "The number you entered is Perfect."
notper:  .asciiz  "The number you entered is NOT Perfect."
prompt:  .asciiz  "Please enter an Integer: "

[userct]

Recently updated my code slightly but still the same errors.

## Registers:
## $s3 Holds the number 1
## $s1: Hold the Sum
## $v2: Counter (May not be used)
## $t3: Integer divided by 2
## $t4: Remainder
## $t5: Divisor
## $t6: Temporary check if less than 1

.text
.globl main

main:
        li      $s3, 1      # Load register $s3 with 1

start:

        li      $t5, 1      # Set the divisor to zero
        li      $s1, 0      # Load the Sum to zero
        li      $t3, 0      # Integer divided by two set to 0
        li      $t6, 0      # Temporary check if less than 1

        li      $t0,4       # access prompt
        la      $a0,prompt  # print prompt
        syscall


        li      $v0,5       # code 5 == read integer
        syscall             # Invoke the operating system.

        divu    $t3, $a0, 2 # Put the integer divided by 2 in $v3

    #BELOW CODE CHECKS IF INTEGER IS <1 and ENDS IF IT IS        
        sltu  $t6,$a0,$s3   #  if ( $a0 < $s3 ) (Int < 1)
                            #    $t6 = 1
                            #  else
                            #    $t6 = 0
        beq   $t6,$s3,end   # Is integer read 1 (meaning above was less than 1)
                            # If so then go to end
        b     run           # Else go to run

    # THIS IS THE END OF CHECKING IF INTEGER < 1 

    # BELOW WILL DETERMINE IF THE INTEGER IS PERFECT

run: 


         remu $t4,$a0,$t5     # divide $a0 by $v5. Put the
                              # remainder in $v4. Operands are
                              # unsigned.



        beqz  $t4,addSum      # If the remainder is equal to zero
        b     check           # Else go to check



addSum: 
        addu $s1, $s1, $t5     # Add the divisor to the Sum

check:
        bgt  $t5, $t3, determine # If register 5 is grater than interger/2
        b    continue            # Else go to continue

continue:
        addiu $t5, $t5, 1    # Increment the divisor by 1

        j run


    # END OF DETERMINING IF INTERGER IS PERFECT

determine:

        beq     $s1, $a0,perfectPrint
        b       notPerfectPrint

perfectPrint:       

        li      $v0,4       # code 4 == print perfect
        la      $a0,perfect # $a0 == address of the string
        syscall             # Invoke the exception handler.

        j start             # JUMP TO THE START OF THE PROGRAM

notPerfectPrint:

        li      $v0,4       # code 4 == print string
        la      $a1,notper  # $a1 == address of the not perfect
        syscall             # Invoke the exception handler.


        j start             # JUMP TO THE START OF THE PROGRAM


end:
        li      $v0,10      # code 10 == exit
        syscall             # Halt the program.


         .data
perfect: .asciiz  "The number you entered is Perfect."
notper:  .asciiz  "The number you entered is NOT Perfect."
prompt:  .asciiz  "Please enter an Integer: "

[userct]

PC = ffffffff80000180
EPC = 0
Cause = 18
BadVAddr = 0
Status = 3000ff12