Hi Tim,
danke für Deine Antwort!
Dass die Hotkeys im minimierten Zustand im Tray nicht funktionieren hatte auch noch jemand anders..
http://dotnet-snippets.de/dns/globale-hotkeys-tastenkombinationen-SID245.aspx (guckst Du bei den Kommentaren)

Hab die HKs mal in der Anweisung, welche das Programm in den Tray minimiert, neu registriert.
Hilft aber leider nichts.
Hier mal der Quellcode..
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Public Class Form1
Inherits System.Windows.Forms.Form
Public WithEvents HK_Klasse As clsHotKey
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Neue Instanz erstellen
HK_Klasse = New clsHotKey(Me)
'Hotkey zuweisen (STRG + ALT + K)
HK_Klasse.AddHotKey(Keys.K, clsHotKey.MODKEY.MOD_ALT Or clsHotKey.MODKEY.MOD_CONTROL, "TASTE_K")
'Noch ein Hotkey zuweisen (STRG + ALT + X)
HK_Klasse.AddHotKey(Keys.X, clsHotKey.MODKEY.MOD_ALT Or clsHotKey.MODKEY.MOD_CONTROL, "TASTE_X")
End Sub
'Event Handler
Private Sub HK_Klasse_HotKeyPressed(ByVal HotKeyID As String) Handles HK_Klasse.HotKeyPressed
Select Case HotKeyID
Case "TASTE_K"
MsgBox("Das war die Kombination STRG + ALT + K")
Case "TASTE_X"
MsgBox("Das war die Kombination STRG + ALT + X")
End Select
End Sub
Private Sub Form1_SizeChanged(ByVal sender As Object, ByVal e As _
System.EventArgs) Handles MyBase.SizeChanged
If Me.WindowState = FormWindowState.Minimized Then
'Hotkey zuweisen (STRG + ALT + K)
HK_Klasse.AddHotKey(Keys.K, clsHotKey.MODKEY.MOD_ALT Or clsHotKey.MODKEY.MOD_CONTROL, "TASTE_K")
'Noch ein Hotkey zuweisen (STRG + ALT + X)
HK_Klasse.AddHotKey(Keys.X, clsHotKey.MODKEY.MOD_ALT Or clsHotKey.MODKEY.MOD_CONTROL, "TASTE_X")
Me.ShowInTaskbar = False
Me.NotifyIcon1.Icon = New Icon("76.ico")
Me.NotifyIcon1.Visible = True
End If
End Sub
End Class