This also happend to me a couple of days ago in a model im working on. Not sure about the exact rotation but it looks very similar!?

Did you make sure you didn't keep these parts grouped with one you where moving without noticing?
It never happened to me so I cannot really fix it. If it is really a bug, it would be great if you can find the sequence of events that leads to it. Therefore I would be able to reproduce it and solve it.

Hi Scrubs,

Its unlikely that I had grouped it with something else because in case of the Robot I tried to delete the skewed group and created it again. But it still ended up in same situation. Mostly it happens when you create a group and then try to attach it to the other group.

I understand that we need to find the steps to reproduce, fortunately I think I can do that, will let you know.

Edit:
Here is one way I could reproduce, hope it helps.
I have created a container and grouped it together, at initial position everything looks fine. I have also verified that the angles are correct to avoid any distortion. If we move the container now in any direction, it will start to distort after certain number of steps.

See the image below (Before moving the object).

Before - Right Bracket by Istaka Citi, on Flickr

And this is the image after moving the object.

After - Right Bracket by Istaka Citi, on Flickr

Some key observations:

1. It happens in both local or global mode.
2. It happens in all three directions.
3. Distortions seems proportional to distance moved.
4. Undo with (ctrl - z) brings it back to original share, but undoing the movement itself (by actually moving it in opposite direction) keeps the distortion.
5. Only certain parts in the group are affected.
   **6. Distortion happens only when moved with keys (No issues with mouse). **

The initial model (with correct positions) is http://mecabricks.com/en/models/Z79a88Ywa8w.
You can try to move the container in this one to see it actually happening. I have deleted and created the container many times and every time I am able to reproduce so seems to be something outside the object.

The final (distorted) state is also saving in separate file @ http://mecabricks.com/en/models/PKbjQ7BkadG.

Relevant images are shared @ [url]https://flic.kr/s/aHskQ4Txoq[/url]

Looks like someone else had this issue too:
http://www.mecabricks.com/en/forum/topic/317

I tried with your initial file to reproduce the error, and I was unable to achieve any kind of skewing. The rotational point of your model is also weirdly off, you might want to try importing into a clean file so everything is centered.

@UmbraManis, did you move it with mouse or keyboard? it doesn't happen when you move the object with mouse. I missed to mention that important point.

This issue is fixed in v5.0 too, great overall update Scrubs thanks a lot.

I rewrote this part of the code. It requires less calculation so less possible bugs.
Good to hear that it is fixed.