When i go to receiving adresses i find one adres: 17nxEdzonsk5muyV2LMMx87vFZSPbj3jSk
when i look it up on the blockchain i see that a transaction has taken place in 2016-06-13.
however i do not see this transaction in my wallet, i still see my bitcoins there.
When looking at this address using the blockchain.info block explorer:
https://blockchain.info/address/17nxEdzonsk5muyV2LMMx87vFZSPbj3jSkyou can see there was an incoming transaction of ~1BTC on 30/11/2013 and an outgoing transaction of ~1BTC on 13/6/2016, leaving a balance of 0.
This basically means the output of tx of 30/11/2013 were used as inputs on 13/6/2016. Either somebody hacked your pc , got your private key and stole your BTC, or you created a transaction using the only input your wallet ever got, and sent your BTC either to yourself or to somebody else.
The only reason why you still see 1 BTC in your wallet i can currently think of is if the wallet isn't sync'ed completely.
In the case you got hacked, and your BTC was stolen, i guess you're out of luck
In the second case (you created a transaction using the only output you got as an input, and sent the BTC to yourself), you might want to make 100% sure you're fully sync'ed.
The btc that were transferred on 13/6/2016 haven't moved since:
https://blockchain.info/address/1CyyfFkwMopGbs3UTAwDtbWyWjgVKAnnLpThis could
potentially mean you sent them to yourself, but because your wallet isn't sync'd, they aren't visible to you yet. It could also mean the hacker hasn't touched his stolen funds after the initial thefth.
I do find it intriguing that the transaction of 2016 has 2 outputs: a big one and an output of 0.001. Having 2 outputs USUALLY means that you sent BTC to somebody and the rest of the BTC was sent to your change address.
In this case, it could potentially mean you've sent 0.001 to somebody and the bulk of your funds was sent to a change address you own, but since your wallet wasn't fully sync'd, you don't know this yet...
My best advice would be: make sure your wallet is sync'ed, make sure your wallet.dat is backupped and make sure your computer is clean and your wallet is encrypted