If you recently bought Flash CS4 and tried to install custom made components you may have experienced that the components were not present under 'Components' in the Flash IDE. First of all in Flash CS3 and CS4 the AS2 and AS3 components appear separate. The AS3 components appear only when you open an AS3 fla file. Where did the components go? If you have a CS4 upgrade installed like I have you will find the components in Flash CS3 in this folder:
C:\Documents and Settings\user\Local Settings\Application Data\Adobe\Flash CS3\en\Configuration\Components
user/Library/Application Support/Adobe/Flash CS3/en/Configuration/Components
So the easiest way to install them in CS4 is to open the 'Components' folder, copy all the files and then go to the same location in CS4 and paste the components.
C:\Documents and Settings\user\Local Settings\Application Data\Adobe\Flash CS4\en\Configuration\Components
user/Library/Application Support/Adobe/Flash CS4/en/Configuration/Components
Now you need to close CS4 and open it again and all the components will be in the components menu.