There is a newer version of APP SDK i.e., version 2.9 available. You might want to try that out. It has a new installer and can be installed via two mechanisms, a Unified web installer or the APP SDK 2.9 full installer. You can download the Unified installers (64-bit) from http://amd.wpengine.com/app-sdk/installers/UnifiedSDKInstaller/1.0/web/AMD-UnifiedSDKInstaller-v1.0-Windows-web-x64.exe and the standalone APP SDK 2.9 installer from http://developer.amd.com/tools-and-sdks/heterogeneous-computing/amd-accelerated-parallel-processing-app-sdk/downloads/.
Please be advised you should only one of the installers, either the Unified web installer or the full APP SDK 2.9 installer.