my runescape was having a lot of lag on the client, it didn't download the game cache, so I removed the complete game through the windows control panel and installed it again.
after that, the game doesn't download, staying in the "downloading client" window
this started on friday and until now it is still stuck in these "downloading client" screens and when it finishes it is stuck in the downloading cache, being necessary to reinstall it to try to correct the problem
I'd try adjusting the graphic settings or re-running the auto-setup. If that doesn't work, try launching the NXT client on compatibility mode or playing from the Steam client.