Problem: When accessing any menu that launches core forms, get this error:

load: class oracle/apps/fnd/formsClient/FormsLauncher.class not found

Solution: Check the proxy server settings in the browser and ensure that addresses to bypass are correct.

Use the ‘hostname*’ format in the proxy server settings.

From Metalink article Doc ID:  Note:291698 (Subject: FormsLauncher.class Not Found Error When Attempting to Access Forms in Applications)

Steps for resolution:

1. Launch a browser window.
2. Go to Connection Settings for the Browser
3. Select the Proxy exception list, the list of sites you have specified, for which no proxy is required
4. Verify / validate all entries in this list.
5. For e.g., you will need to add an entry like *.oracle.com instead of oracle.com to exclude all sites having oracle.com in the domain name
6. Save the changes.
7. Login and access the Applications forms in a new browser window.

See also: Doc ID:  Note:373736.1 (Subject: Load: Class Oracle/Apps/Fnd/ Formsclient/Formslauncher.Class Not Found)