Assumption is the mother of all screw-ups.

Like assuming that IE cache settings haven’t been touched since the last time you tested. Assuming that a final check on a test server is good enough and forgetting the final check in production, is another good example.

Unfortunately the D.E.Y. attitude (Do Everything Yourself) means that I’ve got no one to blame but myself.

So if you’ve tried Do My Invoice lately in IE and had nothing but errors, try again with a CTRL+Refresh (to ensure that IE reloads all files from the server instead of using its annoyingly aggressive cache). You should have a bit more success…