Maybe you should try to boot into Safe Mode and try it there.
Unfortunately, your problem does seem somewhat not so common, indicating a deeper system issue... such as a non-disabled virus scanner (in some cases they need to be uninstalled), or some other issue. Even if you had one installed, and uninstalled it in the past, there still could be remnants on your system.
Try Safe Mode... otherwise, I do not know what it wrong and it would take deeper examination. The comdlg32.ocx file is from Microsoft! So if that one cannot register, then it is a system problem.
Maybe try to register it in a different path, like C:\Test or some other name.