Imovie 11 hangs on start up - /Users

Question

iMovie 11, Mountain Lion 10.8.1 on iMac Intel i7 8Gb RAM. Project and Events on 2Tb USB3.0 disk independent of MichintoshHD.
Hanging on start up. Does not start to load the Project or Event Libraries.
I have read various threads after Googling the issue.
This is what I have attempted so far which hasn't worked
1. in case on issue with large iPhoto library, created a empty photo library and switched iPhoto to that.
2. reinstalled iMovie 11, removing various .plists and cache at the same
3. followed iMovie FAQ post on YouTube http://www.youtube.com/watch?v=2cL9RuDV3Qc. Used OnyX to clean and repair as suggested.
4. removed Flip4Mac WMV Player and repaired disk permissions using DiskUtility
I have left iMovie running over night (8hrs) and still hung in the morning.
However what appears to work is if I create a new user profile and then run iMovie all is good, finding the Project and Event librarys on the USB attached disk. However I have also read that this only works for a period and then the hanging problem reoccurs. I have already had this happen a couple of times but generally its OK. However I don't want to move to this new user profile if the problems are going to reoccur.
Any ideas?
More information below...
On inspecting the process via Activity Monitor, and looking at Open File and Ports, iMovie hangs
/Applications/iMovie.app/Contents/MacOS/iMovie
/Applications/iMovie.app/Contents/Frameworks/iLifeFaceRecognition.framework/Vers ions/A/iLifeFaceRecognition
/Applications/iMovie.app/Contents/Frameworks/Helium.framework/Versions/A/Helium
/Applications/iMovie.app/Contents/Frameworks/Mpeg2TsDecoder.framework/Versions/A /Mpeg2TsDecoder
/System/Library/PrivateFrameworks/iLifeMediaBrowser.framework/Versions/A/iLifeMe diaBrowser
/System/Library/Frameworks/WebKit.framework/Versions/A/WebKit
<... deleted alot of system load stuff to save space ...>
/Users/andrewjones/Library/Preferences
/Users/andrewjones/Library
/Users/andrewjones
/Users
/Users/andrewjones/Pictures/Photo Booth Library
/Users/andrewjones/Pictures
/Users/andrewjones
/Users
/Applications/iMovie.app/Contents/Resources/iMovie '08 Sound Effects
/Applications/iMovie.app/Contents/Resources
/Applications/iMovie.app/Contents
/Applications/iMovie.app
/Applications
/Users/andrewjones/Music/GarageBand
/Users/andrewjones/Music
/Users/andrewjones
/Users                                       
<<<< hangs here for 20mins and then sometimes will start running "Optimizing Movies" to only hang again with following opened
/Users/andrewjones/Pictures/iPhoto Library 2012.photolibrary/Database/apdb/Library.apdb
/Users/andrewjones/Pictures/iPhoto Library 2012.photolibrary/Database/apdb/Properties.apdb
/Users/andrewjones/Pictures/iPhoto Library 2012.photolibrary/Database/apdb/ImageProxies.apdb
/Users/andrewjones/Pictures/iPhoto Library 2012.photolibrary/Database/apdb/Faces.db
Sampling the process shows
    917 Thread_261507: com.apple.appkit-heartbeat
    + 917 thread_start  (in libsystem_c.dylib) + 34  [0x927c2cee]
    +   917 _pthread_start  (in libsystem_c.dylib) + 344  [0x927d8557]
    +     917 __NSThread__main__  (in Foundation) + 1396  [0x993e529b]
    +       917 -[NSThread main]  (in Foundation) + 45  [0x993e5318]
    +         917 -[NSUIHeartBeat _heartBeatThread:]  (in AppKit) + 879  [0x9645aa6d]
    +           917 usleep$UNIX2003  (in libsystem_c.dylib) + 60  [0x92862936]
    +             917 nanosleep$UNIX2003  (in libsystem_c.dylib) + 189  [0x92862a6d]
    +               917 __semwait_signal  (in libsystem_kernel.dylib) + 10,12  [0x97197c72,0x97197c74]
    917 Thread_263259
    + 917 thread_start  (in libsystem_c.dylib) + 34  [0x927c2cee]
    +   917 _pthread_start  (in libsystem_c.dylib) + 344  [0x927d8557]
    +     917 ???  (in QuickTimeComponents)  load address 0x91577000 + 0x5f658c  [0x91b6d58c]
    +       917 TSWaitOnSemaphoreRelative  (in CarbonCore) + 24  [0x98484419]
    +         917 TSWaitOnSemaphoreCommon  (in CarbonCore) + 272  [0x98484190]
    +           917 TSWaitOnConditionTimedRelative  (in CarbonCore) + 177  [0x984846b9]
    +             917 pthread_cond_timedwait_relative_np  (in libsystem_c.dylib) + 47  [0x927dd512]
    +               917 _pthread_cond_wait  (in libsystem_c.dylib) + 938  [0x927dd289]
    +                 917 __psynch_cvwait  (in libsystem_kernel.dylib) + 10  [0x971978e2]
    917 Thread_266203
      917 start_wqthread  (in libsystem_c.dylib) + 30  [0x927c2cca]
        917 _pthread_wqthread  (in libsystem_c.dylib) + 448  [0x927dae19]
          917 _pthread_workq_return  (in libsystem_c.dylib) + 45  [0x927db04c]
            917 __workq_kernreturn  (in libsystem_kernel.dylib) + 10  [0x971980ee]

Answer 1

Thanks for the replies but I have finally worked it out and found the problem.
I had previous had a USB disk connected as a network file share (NAS) device on my wireless router but removed the disk it as never worked very well. I had defined a mount point which I'd forgotten about as it wasn't showing up in Finder. The mount wasn't an issue until I changed my wireless router last week which had a different IP address. I guess iMovie was timing out / hanging waiting for the mount point ; must be unique behavour to iMovie as the iLife products (iPhoto, iDVD, etc), iTunes, etc were all working OK.
Anyway using the Directory Utility (found in System Perferences > User & Groups > Login Options > Network Account Server > Open Directory Utility), I removed the Mount point record (needs a reboot to fully remove) and iMovie back to normal.   If anyone is interested there's more info on network shares here http://images.apple.com/business/docs/Autofs.pdf