Ive had this similar situation, i created an account, put 10m on it at night for starter cash. When i woke up to login the next morning, the 10m was gone, but i was still in the same spot away from a bank. This was literally a 10 hour old account, so nobody knew my pass/login and I have multiple accounts with tons of gold, so it was not a virus or anything because they're all untouched. From my view, it seems my gold just "disappeared" or was "removed" by jagex or something.