I experienced the same syndrome (accessv at 00000000 in the first opencl.dll call) when I uninstalled the latest catalyst and then, after a reset, I installed an older catalyst. Then the opencl.dll was broken.
The solution was:
a) install the latest cat
b) use the AMD Catalyst Uninstall utility right after the regular uninstall. This way older drivers can function well.
Just try realhet's approach for now. FYI, there was a similar issue with W8000 card sometime back, and now it is W7000 card. Both the issues were with 9.003 driver. But an older driver worked for that person. I will let you know if there is any thing more to share.