I can do this because the articles are all named using a standard name:

blecvbsbsXXYY.htm

where XX is the lesson number and YY is the page number. This is complicated slightly because the lessons are also stored on my hard drive in individual folders that also have a standard name:

VBSBSXX

where XX is again the lesson number.

The basic tasks this application will perform, then, are ...

• Display the first page (a default start page for lesson 01, page 01).
• Add 1 to the page number until the Microsoft Web Browser component detects an error, then ...
• Add 1 to the lesson number and restart the page number at 1.

Dim CourseCount As Int16 = 1
Dim PageCount As Int16 = 1

Private Sub Form1_Load {deleted}
    AxWebBrowser1.Navigate({create path string})
End Sub

Private Sub DisplayNextFile_Click {deleted}
    PageCount += 1
    AxWebBrowser1.Navigate({create path string})
End Sub

Private Sub AxWebBrowser1_NavigateError {deleted}
    CourseCount += 1
    PageCount = 1
    AxWebBrowser1.Navigate({create path string})
End Sub

The "create path string" code, by the way, looked like this:

"{constant basic path}\VBSBS" _
	& Microsoft.VisualBasic.Right("0" _
	& CStr(CourseCount), 2) _
	& "\blecvbsbs" _
	& Microsoft.VisualBasic.Right("0" _
	& CStr(CourseCount), 2) _
	& Microsoft.VisualBasic.Right("0" _
	& CStr(PageCount), 2) _
	& ".htm"

This didn't work because the Navigate method inside the NavigateError event would never bring up the first page in the "next" folder. (For example, if blecvbsbs0910.htm, page 10 of lesson 09, didn't exist and triggered the NavigateError event, the new URL, blecvbsbs1001.htm, would never be displayed. It turns out that the execution of event subroutine is suspended after the "404" page not found error is displayed.

You can certainly program around this problem, but the code for doing it isn't simple. Check out this Microsoft MSDN page if you want to dig into it. But there are other ways to accomplish the same goal. This code, which uses the web browser DocumentComplete event, is much less complex and it does work.

Dim CourseCount As Int16 = 2
Dim PageCount As Int16 = 1
Dim urlStr As String
Dim ErrPageNotFound As Boolean = False

Private Sub Form1_Load {deleted}
    AxWebBrowser1.Navigate({create path string})
End Sub

Private Sub DisplayNextLesson_Click {deleted}
    PageCount += 1
    AxWebBrowser1.Navigate({create path string})
End Sub

Private Sub AxWebBrowser1_NavigateError {deleted}
    CourseCount += 1
    PageCount = 1
    urlStr = "{create path string}" 
    ErrPageNotFound = True
End Sub

Private Sub AxWebBrowser1_DocumentComplete {deleted}
    If ErrPageNotFound = True Then
        AxWebBrowser1.Navigate(urlStr)
        ErrPageNotFound = False
    End If
End Sub

The moral of this story is, "Where there is a will, there's a way!"