Progress Bar Freezing Up Cpu Cycles

I have a progress bar on a form......it is there for no reason other than for me to practise such things...the code came off these forums and the bar is powered by a random number...

now my problem is the moment it start running i cannot do anything on the form....i would like my bar to do it's thing but still be able to click on the cancel button to get out of the form any help on this would be fantastic

Private Sub UserForm_Activate()
Dim dTime As Date
Dim i As Integer

Do Until i = 100
For i = 1 To 100 Step 100 / 8
dTime = Now + TimeValue("0:00:01")
Application.Wait TimeValue(dTime) '
ProgressBar1.Value = RandNumGen(1, 98, 1)
'AboutScreen.Repaint
Next i
'AboutScreen.Repaint
Loop

End Sub