The installation could be corrupt, the splash screen is set on the command line and used by the launcher, so it’s possible to see it and not have the plugins successfully load.
The fastest way to correct this is to go to http://www.eclipse.org/downloads, download the Eclipse 3.2 SDK for your platform, unzip it to a *new* location (never overwrite an existing dir), and then fire it up, go to Help > Software Updates > Manage Configuration, right click, do a Add then “New Extension” and point it at your MyEclipse dir, then restart. Do you see the MyEclipse menu and preferences now with this new install? If so, you can just point it at your other workspace so all your projects and preferences are intact, I would suggest restarting using the -clean command line argument atleast once with the existing workspace to clean out old plugin cache information.