Help Problems with browsers -they close by themselves-

[dani_veentox]

Hello, since a few days ago, I'm having some trouble with my browsers (Chrome, Firefox). The problem is that the browsers are closed by themselves -but I think is not crashing, because they continue running in background-
For example: I open Firefox, then 5 seconds (or maybe 20, 50, 1 min, 2min, etc) later they close and brings me to the home screen, the same problem with Chrome.
Then I see the apps running in background and the browsers are still there, opened with all my tabs.
I'm using Android 4.3

 

[Enwyn]

Is the RAM full? Cleaning the memory and cache will usually work. Chrome and Firefox require large amounts of free RAM to run properly, especially if you opened many tabs.

 

[dani_veentox]

Sometimes... YES
But I've tried to clear cache and close all background-running apps and the problem persists (also I've tried to open a few tabs -less than 5-)
The question is, why have this problem appeared a few days ago? One month ago my browsers worked fine :/