XceedZipLib.XceedZipClass loZipper
try
{
loZipper = new XceedZipLib.XceedZipClass();
}
catch
{
MessageBox.Show("Please check to make sure you have the Xceed Zip Compression Library installed",
"Error: Missing Required Files", MessageBoxButtons.OK, MessageBoxIcon.Stop);

return false;
}

Is not the correct way because 1)Hide the others possible error 2)the construc is not in the scope. With try..any and object instantation:

Declare Object

Create Object
try
Accionts
catch
Manage Errors
finally
//not if the object is public or must be returned
Release Object/Close object
end

So i suggest:

Private function GetZip:XceedZipLib.XceedZipClass
loZipper as XceedZipLib.XceedZipClass

loZipper = new XceedZipLib.XceedZipClass()

return loZipper
End Function

funtion Main
loZipper as XceedZipLib.XceedZipClass

try
loZipper=GetZip()
...
catch
Please trap ONLY the creation error, never hide the others
end
End Function