How can you make random movement? - vb.net

Question

I'm doing a simple pacman project on vb.net, and I've come across a great difficulty: how can I make a ghost move randomly, without seeming it is trying to move everywhere at once, which looks like it's spasming?
What I wanted was:
To move the ghost in a random direction (up, left, right or down) and keep that direction until it hits a wall;
When it did hit a wall, determin where it could move, and from the possibilities, choose one and keep that movement until it would hit another wall;
So basically, a loop of that. I'm guessing I definitely need a timer and a loop structure.
This is a picture of the "map":
For example, I've tried this and it doesn't work:
Dim direction As movementdirection
Dim ghostlocation As Point
Dim currentLocation As Point
Dim random As New Random
Public Enum Movementdirection
Up = 1
Down = 2
Left = 3
Right = 4
End Enum
Private Sub redtimer_Tick(sender As Object, e As EventArgs) Handles redtimer.Tick
direction = DirectCast(random.Next(1, 5), Movementdirection)
Select Case direction
Case Movementdirection.Down
red.Top += 2
Case Movementdirection.Up
red.Top -= 2
Case Movementdirection.Left
red.Left -= 2
Case Movementdirection.Right
red.Left += 2
End Select
direction = DirectCast(random.Next(1, 5), Movementdirection
End Sub
Public Function DetectCollection(ByVal red As PictureBox) As Boolean
For Each wall As PictureBox In WallList
If red.Bounds.IntersectsWith(wall.Bounds) Then
direction = DirectCast(random.Next(1, 5), Movementdirection)
End If
Next
ghostlocation = red.Location
Return False
End Function
I've also tried this and didn't work that well, he also spasms.
Private Sub redtimer_Tick(sender As Object, e As EventArgs) Handles redtimer.Tick
Select Case direction
Case Movementdirection.Down
red.Top += 2
Case Movementdirection.Up
red.Top -= 2
Case Movementdirection.Left
red.Left -= 2
Case Movementdirection.Right
red.Left += 2
End Select
num = Int((4 * Rnd()) + 1)
If num = 1 Then
direction = Movementdirection.Down
End If
If num = 2 Then
direction = Movementdirection.Left
End If
If num = 3 Then
direction = Movementdirection.Right
End If
If num = 4 Then
direction = Movementdirection.Up
End If
If Not WallList.Any(Function(wall) wall.Bounds.IntersectsWith(New Rectangle(location:=New Point(red.Location.X, (red.Location.Y + 2)), size:=red.Size))) Then
red.Location = New Point(red.Location.X, (red.Location.Y + 2))
Else
End If
If Not WallList.Any(Function(wall) wall.Bounds.IntersectsWith(New Rectangle(location:=New Point(red.Location.X, (red.Location.Y - 2)), size:=red.Size))) Then
red.Location = New Point(red.Location.X, (red.Location.Y - 2))
End If
If Not WallList.Any(Function(wall) wall.Bounds.IntersectsWith(New Rectangle(location:=New Point((red.Location.X + 2), red.Location.Y), size:=red.Size))) Then
red.Location = New Point(red.Location.X + 2, red.Location.Y)
End If
If Not WallList.Any(Function(wall) wall.Bounds.IntersectsWith(New Rectangle(location:=New Point(red.Location.X - 2, red.Location.Y), size:=red.Size))) Then
red.Location = New Point((red.Location.X - 2), red.Location.Y)
End If
End Sub