For the last few updates, I've been unable to get idea64.exe to work right. It would hang on startup, use more RAM than vmoptions specified, or the UI would freeze. I always resorted to having to use the idea.bat file pointing to a 64-bit JDK.
I just downloaded the latest 10.0.3 update, updated the (new) idea64.exe.vmoptions to use the VM args I need, and launched idea64.exe. This time, it launched and loaded my project without a hitch!
(FWIW: I'm running Windows 7 64-bit Ultimate; Oracle/Sun's 64-bit 1.6.0_24 JDK; 24 GB RAM; Intel i7 3.2GHz.)
Thanks for the update!
PS. For anyone using idea.bat to launch, I found if I changed the batch file to use javaw.exe instead of java.exe, I'd still get the console window, but could safely kill it once IDEA started. It would be nice if it closed automatically (or never showed), but at least I can close it.