IPhoto crashes immediately on launch

Question

I have a 2013 iMac 27" running 10.9. Many apps crash regularly, but now I have a reproducible case. Whenever I launch iPhoto, it displays a the main window with a spinner and then crashes. The crash log contains this information:
com.apple.launchd.peruser.501[167]: (com.apple.iPhoto.29424[1393]) Job appears to have crashed: Segmentation fault: 11
The crash report from iPhoto contains this information:
Process:         iPhoto [1393]
Path:            /Applications/iPhoto.app/Contents/MacOS/iPhoto
Identifier:      com.apple.iPhoto
Version:         9.5.1 (902.17)
Build Info:      iPhotoProject-902017000000000~3
App Item ID:     408981381
App External ID: 233642646
Code Type:       X86-64 (Native)
Parent Process:  launchd [167]
Responsible:     iPhoto [1393]
User ID:         501
Date/Time:       2013-12-17 20:53:18.862 -0800
OS Version:      Mac OS X 10.9 (13A603)
Crashed Thread:  0  Dispatch queue: com.apple.main-thread
Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: EXC_I386_GPFLT
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   com.apple.iPhoto                        0x0000000100155383 0x1000fb000 + 369539
1   com.apple.Foundation                    0x0000000105328dbd _NSSetObjectValueAndNotify + 269
2   com.apple.iPhoto                        0x000000010015111f 0x1000fb000 + 352543
3   com.apple.iPhoto                        0x0000000100150ab2 0x1000fb000 + 350898
4   com.apple.iPhoto                        0x000000010014fb73 0x1000fb000 + 346995
5   com.apple.iPhoto                        0x000000010010e765 0x1000fb000 + 79717
6   com.apple.Foundation                    0x0000000105320c57 __NSFireDelayedPerform + 333
7   com.apple.CoreFoundation                0x0000000101557724 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
8   com.apple.CoreFoundation                0x000000010155725f __CFRunLoopDoTimer + 1151
9   com.apple.CoreFoundation                0x00000001015c876a __CFRunLoopDoTimers + 298
10  com.apple.CoreFoundation                0x0000000101512aa5 __CFRunLoopRun + 1525
11  com.apple.CoreFoundation                0x0000000101512275 CFRunLoopRunSpecific + 309
12  com.apple.HIToolbox                     0x000000010b002f0d RunCurrentEventLoopInMode + 226
13  com.apple.HIToolbox                     0x000000010b002cb7 ReceiveNextEventCommon + 479
14  com.apple.HIToolbox                     0x000000010b002abc _BlockUntilNextEventMatchingListInModeWithFilter + 65
15  com.apple.AppKit                        0x000000010959228e _DPSNextEvent + 1434
16  com.apple.AppKit                        0x00000001095918db -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
17  com.apple.AppKit                        0x00000001095859cc -[NSApplication run] + 553
18  com.apple.AppKit                        0x0000000109570803 NSApplicationMain + 940
19  com.apple.iPhoto                        0x000000010010b2ff 0x1000fb000 + 66303
20  libdyld.dylib                           0x0000000105b8b5fd start + 1
The particular exception, EXC_BAD_ACCESS (SIGSEGV), is part of most of my crash reports. At this point, I'm thinking I might just wipe my HD and only copy over files from a backup as I need them, but I'm wondering if anyone has ideas before I do that.

Answer 1

Please read this whole message before doing anything.
This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.
Step 1
The purpose of this step is to determine whether the problem is localized to your user account.
Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your personal files or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.
Step 2
The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Boot in safe mode and log in to the account with the problem. Note: If FileVault is enabled on some models, or if a firmware password is set, or if the boot volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to boot and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal boot may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, reboot as usual (i.e., not in safe mode) and verify that you still have the problem. Post the results of steps 1 and 2.