Not sure if this is the same, but.
 
In X3e I have a new project. It has 14 audio tracks and NO plugins, completely raw.
 
I was muting the guitar track and listening to the bass in relation to the kick and snare for timing issues.
 
This required me to stop and restart the audio engine to here the specific part I was interested in.
 
I did NOT create a loop for this.
 
After about three repeats the audio engine quite and I got the dreaded "drop out" warning in my lower right corner.
 
This happened three times and then I stopped reviewing it.
 
What is up. I don't have any plug ins running, and no soft synths or anything, just basic audio tracks for drums, bass and guitar.
 
Thanks.

I narrowed this issue down to the fact that I was using a wireless Keyboard/ mouse combo. I like it so I can move away from the workstation for vocals.. but it can be none responsive and sluggish. 
You type and there is a delay. 
So I now have both hooked up, a wired and the wireless. 

Temojem, I recommend you start a new thread. Your issue sounds like a relatively garden-variety ASIO/disk buffer tuning issue (most likely disk buffer in this). Pursuing it in this old, probably unrelated, thread will just confuse everyone.