When I double click on ChemDraw 3.x (.CHM) files to open them, Microsoft Help tries to open the file and can't.
Many new programs are using Microsoft's HTML-based help system, for which the help file extension is .CHM ("compiled HTML file"), which happens to be the same as our old ChemDraw 3.x extension. We have no control over another company using the same extension for something else. The latest version of ChemDraw uses a newer file format and extension (.CDX).
There are a few options.
- Upgrade to the latest version of ChemDraw, which uses the .CDX extension as the default file format. Once you upgrade, you can rename all of your old ChemDraw files with a .CHM extension to .CDX. PLEASE NOTE: ChemFinder for Word will not find CHM files that have been renamed to CDX. You would actually need to resave each file as a new CDX file instead of rename the files if you wanted ChemFinder for Word to detect them. If you have many ChemDraw files with the .CHM extension, you can use the DOS "Rename" command to rename all of your .CHM files to .CDX at once. To do this:
- Create a new folder on the top level of your C drive called CONVERT. Put all of your ChemDraw .CHM files into this new folder.
- Using the MS-DOS command prompt, change the directory to CONVERT (for example, at the C:\ prompt type "cd CONVERT" so the path is now "C:\CONVERT\")
- Now do a Rename by typing: "Rename *.* *.CDX
- This will add a .CDX extension to every file in the CONVERT folder.
- In Windows 95 and NT 4, you can open the Windows Explorer, and choose Options from the View menu. Click on the File Types tab. Look for IE4's Help application that uses the .chm extension. Select it and choose Edit. You can now edit this to be the ChemDraw application for opening and printing. You can also edit the icon too, so that ChemDraw .CHM files have the appropriate icon.
- You can reinstall ChemDraw and it will set ChemDraw as the default for .CHM files. However, there will still be a conflict. The .CHM extension can only be set to one application or the other.