How to diagnose repeated OS X hang / spinning beach ball of death?

@Ashley mentioned it could be related to file corruption in Keychain files. Not widely known but KeyChain has its own First Aid utility which can be used to Verify or Repair the keychain files.

Just invoke from the Keychain menu:

Worth checking?

My interpretation (which could well be wrong) of that error report is:

• the crsud process, which apparently is to do with security (code signing, software update and trust evaluation: see this discussion), has crashed.

• it did so whilst it was running code related to the keychain (under "Thread 0 Crashed", start at the last entry (33) and read upwards, to see the different routines that are called): I noticed Security::KeychainCore::CCallbackMgr...

• the type of error was EXC_BAD_ACCESS, which is a failure when accessing memory.

• the area of memory it was trying to access was actually a file mapped into memory, and the file(s) were /private/var/db/*.

So actually, I'd be suspicious of your hard disk, rather than the RAM, and particularly files under /private/var/db and any related to the Keychain. I would try Repair Disk in Disk Utility as a first step. (You will need to boot from another location to do this.)

Sorry this isn't a complete answer (and bear in mind some of this is guesswork), but perhaps it provides another direction for things to try?

From your original question there isn't enough strong evidence this is an hardwrae or software problem.

Hardware problem?

To eliminate most of the hardware origins, please run: Apple Hardware Test before attempting any other tinkering with the system.

Run it in extended mode and for at least 4 consecutive passes.

Once this 1st cause of trouble eliminated, please read the answer from Ashley and run Disk Utility from another disk than your system one. Most probably your internal filesystem is in bad state since you regularly crash your system. Hence at every new boot the journal (of the filesystem) has to be used again to rebuild everything, and long processes killed have to start again their tasks.

Once this 2nd major cause of trouble eliminated, you will conclude that you most probably have a software problem, and it might be time to locate it.

Software problem

For this you will have to create a test account and use it for a serious amout of time, and with all the applications. Do you experience the same hangs with this test account?

If yes, then you have a general MacOS X misbehaviour. In this case, you have to reinstall MacOX X Lion.

If not, you will have to locate which application within your environment is causing this misbehaviour.

Activity Monitor will help you to identify what is going on when MacOS X stop being responsive. Until you will find the culprit, you will have to always run with this kernel spy on screen. Another tool might be faster to identify the culprit processus. Open a Terminal or xterm window and type the following command:

top -o cpu

the top lines continuously refreshed by this command will show you if something abnormal is happening at the level of virtual memory or CPU usage, within seconds of the original problem.