Bitcoin-Qt works properly, but during exit it crashes everytime with the same error:

http://www.wavestock.com/images/bitcoin%20runaway%20exception.png

I've searched a bit the web and found this :

https://github.com/bitcoin/bitcoin/issues/2701

2 QUESTIONS :

1. Why did this happen in the first place ?
2. How do I solve this problem ? It looks like I could "Recover using -salvagewallet." => what does it mean ? How do I do this ? Is it within Bitcoin Qt that I need to do something ?

Other solutions propose to delete all the dat files, except the wallet.dat but I'm not sure if that's a good solution. This is the folders and files I see in my Bitcoin folder:

http://www.wavestock.com/images/bitcoin%20runaway%20exception2.png

Thanks for your help.

cousinHub

PS: I have my bitcoins in another Wallet in Armory but still I would like to understand what happens and clean up this error.