But just the other day I think I found the dumbest reason I could ever think of: To get an older version of Internet Explorer - and I don't even use IE!
Two questions come to mind - why would I want an older version of a programme I don't even use, and, if I was so desperate, why not just download one from the MS website?
The downloading thing is easy to answer: Windows 7 comes with IE8 pre-installed, and if you "upgrade" it to 9 or 10 (especially 10) either manually or via Windows Update, you can't actually "roll back" - Windows won't let you install an older version, so the installer fails.
So why would I want to do this? Recently I was toying around with a bunch of different IDE's - everything from the Orwell strain of Bloodshed, to Code::Blocks, to proprietary interests (just to see if they do anything different).
Back when I was a kid, the best thing in the world was the Turbo C IDE from Borland... I lovingly spent thousands of hours staring at this sort of thing...

I remember spending a year and half saving up my 200-quid to buy it, and gloriously paging through the manuals and the thousand pages of function references, all laid out in a nice clear manner for the beginner - and all of it printed on real paper! I paged through those references so much I wore out the binding and the books began to fall apart so I separated everything out into 3-ring-binders to preserve it even longer.
Did you hear me? I said REAL PAPER! Oh, to kill a tree for a noble purpose again! Whatever happened to the good old days?
The irony, of course, is that back then products only shipped with paper - they didn't start shipping with digital copies (not even text files) until later, so even simple things like <F1> highlighted contextual help didn't amount a much more than "This is how you compile things" - not true function references or anything as useful as that.
Much like Jesus between the ages of 13 and 30, very little is known about my life from 18 to 35 (I went wandering into the desert and never touched a computer again) - so I came back very late to the IDE game, and grew to be quite happy with <F1> contextual help, especially as found in the offline MSDN libraries supplied with Visual Studio.
Say what you will about MS, but it's almost universally agreed that they make one of the best IDE's (especially that integrated documentation), so I dug out an old copy of VS2008 (because I had an Academic license for it - don't ask), and sought to play with it. It seems in the more recent versions of VS, MS has removed the capacity to install offline versions of MSDN assuming that everyone just uses the internet these days. This is not always practical, so I wanted it done right.
Great - except for one thing: the contextual help for VS2008 only works with IE8 - it does not work with IE9 or 10 because every single page requested brings up a content-conflict which the new security protocols reject, forcing the user to manually verify each and every page - there is no way to disable this permanently. I know this because I wasted half-a-day trying.
So, the simplest way to get back to IE8 is to just reinstall Windows, which (at this late date) combined with the necessary updates for VS2008, inclusive of service packs and nonsense .NET updates, requires the better part of a day and over a GB of downloading.
At least it works.
Now I just have to figure out how to reinstate all the necessary tweaks I conjured up over the last 24 months.
On the plus-side, at least I remembered to set up AHCI mode in the BIOS first this time, so that's one less tweak I need worry about. SATA IDE is truly dead.

