I justed moved from a 32 bit laptop to a 64 bit laptop. The project we are working on uses Acrobat Reader activex control to show PDF documents. When I ran the project on my system from VS 2008 the application threw exception while trying to load the PDF viewer control. The error returned was
"Class not registered HRESULT 0x80040154..."
The issue turned out to be that the solution was compiled for "Any CPU"\x64 bit architecture. Once i changed the build configuration to x86 and recompiled the error was resolved. It intially seemed like the component was not installed correctly and i tried to reinstall Acrobat Reader multiple times before hitting the correct solution.

Happy Coding