W3 cache emtying shopping cart

Our web-shop worked fine untill the 27. february then suddenly it emtyied the shoppingcart, so the session handler was not working. I then called my host because I thought the mistake was by them but we found out by inactivating w3 total cache and emtying cache afterwards. Our web-shop worked again. Now my question is what happend I have done nothing in terms of changing on my website it suddenly just didn’t work anymore. Did anyone else experiece this and what now should I try to activate again and risk that it will do the same all over or is there something I should write in the script to avoid this to happen.
Looking forward to any answer that can help with this.