It happens in linux wallets, windows or both?
mac wallet is this safe to use
It is perfectly 'safe' in using any version of the client as long as you DO NOT encrypted your client or by keeping a working backup of the encrypted client (wallet.dat) before you create any new address every time.
This possible bug with the client is NOT RELATED to hacking of any sort, my best guess and what I am focusing now is that the bug could be related to how the client generate new address in an already encrypted client and possibly in some circumstances affected the wallet.dat file making it impossible to get the client to unlock even with the correct passphrase.
My first priority right now is to try to duplicate the issue and try to find the real cause of the bug.
I have tried to get in touch with xCash developer since their users is apparently also affected by the same 'possible bug' but still haven't heard back from him so far.
Thank you all for understand and support.