At Tue Aug 01 2017 10:00:00 GMT+1000 (AEST), Bitcoin confirmation scores may become unreliable for an unknown length of time. This means that any bitcoins you receive after that time may later disappear from your wallet or be a type of bitcoin that other people will not accept as payment.
Once the situation is resolved, confirmation scores will either automatically return to their normal reliability or there will be two (or more) competing versions of Bitcoin. In the former case, you may return to using Bitcoin normally; in the later case, you will need to take extra steps in order to begin safely receiving bitcoins again.
For further information and future updates, follow this link: https://bitcoin.org/en/alert/2017-07-12-potential-split