For Loop Randomly Freezes

[cx323]

For i = 0 To 9999
    
    strHTML =    'get the source.  i know it gets the source correctly even when it freezes
 
    If InStrB(1, strHTML, "this") <> 0 Then
        x = x + 1
        Label2.Caption = x
    ElseIf InStrB(1, strHTML, "or this") <> 0 Then
        x = x + 1
        Label2.Caption = x
    ElseIf InStrB(1, strHTML, "thisthis") <> 0 Then
        x = x + 1
        Label2.Caption = x
    Else
        add_log strHTML
        lstlog.AddItem Time & " Found it"
    End If
    DoEvents
    Sleep 10
    Pause (1)
Next i

I'm not sure why it's freezing. It's frozen anywhere from the 2nd time to the 38th. Also if you could tell me why it uses 100% of the cpu even with a pause adn DoEvents that would be great. Thanks for any help