For 1 thing, you are trying to save the file twice which can cause the popup. Also if you already ran this script, then c:\WorkBook.xls will already exist.
I don't think you can handle that popup within the code per se. You should look up the help for SaveAs (workbook version) which has an optional prameter not to display the "conflict resolution dialog" that you are trying to close.
So you need to check if that file already exists in your code or delete it before you run - and only try to save it once. See MSDN website for File System Object help too.
Also, since you are not cleaning up the objects, this script leaves and Excel process running each time which can be seen in Windows Task Manager, you need to close the Excel object to avoid this memory leak (leaving this open can also lock the object so that it can't be deleted either). Another good practice is to set the objects to Nothing, though that doesn't matter in this case since the script ends, which does the same thing.
Here is a version of your script that checks for the file, deletes it if there, then save's the new workbook.
<font class="small">Code:</font><hr /><pre>Set objApp = CreateObject("Excel.Application")
Set objWorkBook = objApp.Workbooks.Add()
Set objFSO = CreateObject("Scripting.FileSystemObject")
strFile = "c:\WorkBook.xls"
If objFSO.FileExists(strFile) Then
Set objFSO = Nothing
Set objWorkBook = Nothing
Set objApp = Nothing
A problem is a difference between what is perceived and what is desired, that
we want to reduce (Dewey 1933)