I can't find the cause of this Stack Overflow Exception - vb.net

Question

Ever since I added the CheckForCollision_Enemy method, I've been getting a stack overflow exception every time I run my code.
Here is the CheckForCollision_Enemy method, in the Main class.
Public Sub CheckForCollision_Enemy()
Dim ship1 As New Enemy(Nothing, Nothing)
Dim ship2 As New Enemy(Nothing, Nothing)
Debug.Print("")
Dim ships = {acc_e, bs_e, sb_e, ds_e, pb_e}
For i As Integer = 0 To ships.Length - 1
ship1 = ships(i)
For j As Integer = 0 To ships.Length - 1
ship2 = ships(j)
If ship1.name <> ship2.name Then
For l As Integer = 0 To ship1.length - 1
For t As Integer = 0 To ship2.length - 1
If ship1.space_filled(l, 0) = ship2.space_filled(t, 0) And ship1.space_filled(l, 1) = ship2.space_filled(t, 1) Then
Debug.Print("Collision at {" & ship1.space_filled(l, 0) & ", " & ship1.space_filled(l, 1) & "} " & ship1.name & " VS " & ship2.name)
End If
Next
Next
End If
Next
Next
End Sub
Here is the Enemy class. This is the class where the error is shown. I marked exactly where as a comment.
Shared gen As New Random()
Dim x As Integer = 0
Dim y As Integer = 0
Public Sub New(ByVal namep As String, ByVal lengthp As Integer)
name = namep
length = lengthp
ReDim _start_point(2)
ReDim _space_filled(length, 2)
GenerateDirection()
If direction = "horizontal" Then
x = gen.Next(0, 11 - length)
y = gen.Next(0, 10)
ElseIf direction = "vertical" Then
x = gen.Next(0, 10)
y = gen.Next(0, 11 - length)
End If
GenerateStartPoint()
ExtendStartPoint()
DefineFilled()
ColorFilled()
Main.CheckForCollision_Enemy() 'If this is taken out, it will work fine.
End Sub
Public Sub GenerateStartPoint()
start_point = {x, y}
End Sub
Public Sub GenerateDirection()
If gen.Next(0, 2) = 0 Then
direction = "horizontal"
Else
direction = "vertical"
End If
End Sub
Public Sub ExtendStartPoint()
If direction = "horizontal" Then
For i As Integer = 0 To length - 1
space_filled(i, 0) = start_point(0) + i
space_filled(i, 1) = start_point(1)
Next
ElseIf direction = "vertical" Then
For i As Integer = 0 To length - 1
space_filled(i, 0) = start_point(0)
space_filled(i, 1) = start_point(1) + i
Next
End If
End Sub
Public Sub DefineFilled()
For i As Integer = 0 To length - 1
x = space_filled(i, 0)
y = space_filled(i, 1)
Try
generate = False
Main.TrackerBoard.box_list(x, y).full = True
Catch
End Try
Next
End Sub
Private Sub ColorFilled()
For y As Integer = 0 To 9
For x As Integer = 0 To 9
'Debug.Print(Main.PlayerBoard.box_list(x, y).full)
If Main.TrackerBoard.box_list(x, y).full = True Then 'New error: "InvalidOperationException"
Main.TrackerBoard.box_list(x, y).image.BackColor = System.Drawing.Color.Red
Else
Main.TrackerBoard.box_list(x, y).image.BackColor = System.Drawing.Color.Silver 'Most often, the error appears here.
End If
Next
Next
End Sub
Here is the ship class. I've taken out most of the methods to save space; if you want to see anything, I'll add it in for you.
Public Class Ship
Dim _name As String
Public Property name() As String ...
Dim WithEvents _image As PictureBox
Public Property image() As PictureBox ...
Dim _length As Integer
Public Property length() As Integer ...
Dim _direction As String
Public Property direction() As String ...
Dim _selected As Boolean
Public Property selected() As Boolean ...
Dim _placed As Boolean
Public Property placed() As Boolean ...
Dim _location() As Integer = {0, 0}
Public Property location() As Integer() ...
Dim _has_moved As Boolean
Public Property has_moved() As Boolean ...
Dim _space_filled(,) As Integer
Public Property space_filled() As Integer(,) ...
Public rect As System.Drawing.Rectangle
Dim mouse_up As Boolean = False
Dim tile_size As Integer = 25
Public Sub New(ByVal namep As String, ByVal imagep As PictureBox, ByVal lengthp As Integer, ByVal directionp As String, ByVal selectedp As Boolean, ByVal placedp As Boolean)
name = namep
image = imagep
length = lengthp
direction = directionp
selected = selectedp
placed = placedp
location(0) = 0
location(1) = 0
ReDim space_filled(length, 2)
rect = New System.Drawing.Rectangle(location(0), location(1), length * tile_size, 1 * tile_size)
End Sub
Private Sub Ship_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _image.MouseMove ...
Private Sub Ships_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _image.MouseClick ...
Private Sub Ship_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles _image.MouseUp ...
Public Sub Update() ...
Public Sub SnapToBox() ...
Private Sub DefineSpaceFilled() ...
Private Sub ColorFilled() ...
End Class

Answer 1

Your CheckForCollision_Enemy calls New Enemy, and New Enemy calls CheckForCollision_Enemy. You are recursing until the stack overflows.