I had this same problem. What I did to overcome this problem is login to the web server, and try accessing Reporting Services. I would instantly received the following error message:
Unable to find script library '/aspnet_client/system_web/1_1_4322/webuivalidation.js'. Try placing this file manually, or reinstall by running 'aspnet_regiis -c'.
I did as the error message asked and was able to get a response from the buttons when I clicked on them. I hope this helps.