I suggest you check your system Event Viewer's security log and your settings for UAC and so on. Often this failure to launch is caused by security settings preventing one app calling another. That also extends to virus scanners and otehr tools you may have on the system and that encapsulate programs/ processes for security reasons.
This is an old thread but I found it because I had the same problem with a newly installed Windows 7 and brand new AE as part of the Master Suite. None of the ways to start Bridge from inside AE worked (Brose in Bridge, Browse Template Projects or Browse Presets). I'm just a new user trying to follow the exercises in Classroom in a Book... not a complete idiot but new to this.
Anyway, after a LOT of random messing around (grrrr...) I looked in "show hidden icons" at the bottom right of my screen and found to my surprise that the Bridge icon was there even though it wouldn't start from AE. I right clicked on it and unchecked "Start Bridge at login" and oddly it now works perfectly from within After Effects.
Might help someone else.
Thanks for sharing your thoughts. Launching Bridge on system startup should not have any influence but it's good to know it may interfere.
Unchecking "Start Bridge At Login" also worked for me. Bridge now launches from within AE
Bridge would launch from Photoshop prior to unchecking in Bridge preference/advanced, so this issue may be just an AE problem.
Windows 7, CS5.5.
I also couldn't launch Bridge from within After Effects. I tried Amanda's work-around and it worked. I unchecked "Start Bridge at Login" in the "show hidden icons" menu, lower right of task bar and Bridge now launches from within AE.