Illogical, Jim
Were Mr Spock around, he would have some observations to make about some of the things that software says and does. These are not necessarily bugs but sometimes just questionable design ideas.
Anything that looks like a number
? This one always raises a smile. How do I know that what you think looks like a number is the same as what I think looks like a number?

The following message from nickserv on – Freenode I guess – doesn’t quite make sense. Does it make me someone else? Is this a split personality diagnosis?

The following error was highlighted on the Windows Crash Gallery a long time ago and I was amused yet dismayed to see that Excel still persists with its meaningless assertion.

How can I have a Sent column of a drafts folder? Isn’t there an element of mutual exclusion there somewhere?

Mackie showed me that Entourage has exactly the same problem:

And this one is really weird: a smiley in a control name? And how comes most of what comes up in that list isn’t anything I want to base a new file type on in the first place?

I produced the following spreadsheet, I imagine, as a test of graphing on the Psion Revo for an article on EPOC:

But when I generated a graph, I got decimal points in the Y axis: {0, 0.5, 1, 1.5, 2 …}. I found this somewhat perplexing given that all the Y values were integers. So I adjusted the axis settings to switch off decimal places. Whereupon it simply rounded all the numbers thus:

Fantastic.
I tried Open With on a text file in Explorer, and received the following list of recommended
associations:

Upon what, pray tell, are these recommendations based? Taking the primary recommendation, I receive this:

D’oh?
Finally, Mr Spock would have a field day with the following set of conflicting messages encountered when trying to get my office PC’s speaker to bleep:
Let’s recap. I don’t need a speaker driver and one is not loaded but I can uninstall the non-existent driver anyhow, as well as install a replacement to the one that is already installed but apparently isn’t? It is clarity of vision like this that keeps the well-oiled machine of Windows running so smoothly.
(Sorry about the truncated image; trying to keep the width down!)
