There is one UI instance of Excel 2007 up with an error message and
when I try to instantiate the worksheet component through VB.Net I get
this error: It seems that the UI instance is blocking access to the
worksheet component.

VB.Net Error:
"Creating an instance of the COM component with CLSID
{00020820-0000-0000-C000-000000000046} from the IClassFactory failed
due to the following error: 80010001."


Excel UI Error:
The file you are trying to open test.xls is in a different format than
specified by the file extension.

VB.Net Code:
Dim MainWorkSheet As New Microsoft.Office.Interop.Excel.Worksheet