Hello, first post i hope it helps. I had the same issue and tryed al kind of things suggested in these forums but finaly just tried something myself and it worked like a charm. What i did was;
0: Installed the Microsoft DHTML Editing Control first
1: Install Book Designer (BD) and update directly to the C:\ as suggested in one og the help threads (C:\Book Designer 4.0)
2: When trying to run BD i got the "component 'comdlg32.ocx' or one..." message i said ok and the program closed, i then found the file in C:\Windows\System32 and right clicked on COMDLG32.OCX and selected "UnRegister" then ok on the pop up that apperes. Then i rightclicked the same file again and selected "Register" and ok angain on the pop up.
3: After COMDLG32.OCX when trying to run BD i got an the same error message but with COMCTL32.OCX and just repeted the same steps as above.
After that it worked, and all was well in the world