"Run-time error ‘339’: Component ‘MSCOMCTL.OCX’ or one of its dependencies not correctly registered: a file is missing or invalid" during ChemDraw installation.

Please try the following steps as a workaround:

1. Move the downloaded installer (cos_version_number.exe) to your Desktop and create a new folder on your Desktop with the name COS
2. Right-click the installer (cos_version_number.exe) and select “Run as Administrator” from the context menu.
3. The wizard asks you to point to the folder where you need to place the extracted installer, click the browse button and point to the COS folder and click the OK button.
4. After extraction, close the wizard and browse to the folder and locate the “MSCOMCTL.OCX” file location, copy/paste the file in the following location: C:\Windows\System32
5. Right-click on the Start then select Command Prompt (Admin) or right-click search for cmd then select "Command Prompt" from the search hit right-click and select Run As Administrator, you need to allow the program by clicking the Yes button in the "User Account Control" dialog box
6. At the command prompt, type Regsvr32 and a space.
7. Type the full path of the MSCOMCTL.OCX file in this command line after regsvr32.
eg: regsvr32 “C:\Windows\System32\MSCOMCTL.OCX”
8. Press ENTER key.
9. Quit the command prompt.
Then retry the installation. 

If you still run into any problems, then open the COS folder present on your Desktop and browse to the \PerkinElmer\ChemOffice folder and run the following installers one by one manually:
PerkinElmer_ChemOffice_Suite_....msi
PerkinElmer_ChemOffice_64-bit_Support_...msi

After completing the installation browse to \PerkinElmer\ChemScript folder and run the following installer (For v18.x/19.x/20.x/21.x)
PerkinElmer_ChemScript_....msi (if you have 32-bit MS Office)
or
PerkinElmer_ChemScript_..._x64.msi(if you have 64- bit MS Office)

Then Launch ChemDraw as an Administrator on your Windows machine.
Click the Windows Start button then Browse to ChemDraw (present under ChemOffice 20xx), select and then right click then click on More and then select "Run as Administrator".
It will open the "Software Activation" window (otherwise select "Activate ChemDraw...." from the Help menu).
Enter your Name, and email account, and copy/paste the activation code into the activation code text box.
Then click the "Activate" button.