Paint was always such a shit that many people actually called it MS Pain.
Microsoft has been fixing many things from version to version, making the one that ships with Windows XP even quite usable. Following versions were even bigger steps, with final version (Windows 7) actually rewritten from scratch, using ribbon, multi-level undo and many, many more.
Pity, that with one of the last version they removed a "small" feature that was always there -- a warning screen to warn you that you are about to loose your work...
A palette reduction without a warning
What I'm talking about is the removal of warning that appeared during saving images, if you tried to save a bitmap with smaller palette size than your actual picture uses.
An example: You're editing a Full Color image in Paint, with thousands of colors. When saving it, you pick 16-color bitmap.
In older version of Paint, you were always notified that when you continue, your image may become distorted or have really bad quality, due to too low number of colors used. It was very important warning, because Paint hasn't got any professional dither or color-reduction algorithms coded. So, if it reduce your color palette, in 95 on 100 attempts, it will do a real shit out of your pretty picture.
Now, when creating new edition of Paint, some extreme moron at Microsoft figured out, that it will be so cool to remove this warning message.
So, you open a photograph with a millions of colors, save it with 256 colors and Paint says: "OK, I don't give a damn shit that I am about to ruin your work!" and continues with saving without warning you about anything.
No on-screen update
To make things even worse, in older version of Paint, actual on-screen image was updated right after save, to the one, you have on the disk (with the limited palette; ugly looking). So, right after save, you were aware that your beautiful picture was turned into an absolute piece of shit.
You could at least try to do something. Use Undo function or paste image again, if you still had it in clipboard. Most times you were actually deeply in black ass, without possibility to do anything, but at least you were aware of that fact. And that's always something.
Now, for the reason beyond my imagination, the same or another extreme moron at Microsoft had decided that you don't need this as well.
Now, when you save your beautiful image in lower color palette then required, you'll still see the same beautiful image in Paint. Even though, you have a shit written to your disk. So, right now, you see image different that you have saved!
Summary
It is like you would have "Ode to Joy" (Anthem of United Europe) lyrics written in Word, then you would save it to disk, Word would actually written "La Marseillaise" (Anthem of France) and would not update your text in the editor, claiming, that both texts are identical.
That passes even my limits of stupidity and fuckups.
But, hey, after all -- this is Microsoft, right?