Finder window opened in other apps (e.g. open / save as) freezes app

Question

Hi, I have been running Mavericks 10.9.1 without any problems for the last couple weeks, since two days ago applications have been freezing up / going into endless loops (requiring force quit) whenever I open the finder pop-up to look for files to open or to "save as" within the app. E.g. Mail - choosing files to attach to a mail, or opening the "save as" dialog in any program and choosing a folder anywhere in the file system causes the application to hang. I have submitted the log files. In one or other of them (but not all) the message "Too many threads open" (or something approx. like it) was about the only understandable thing I could see. I checked the number of open threads using activity monitor but there didn't seem to be an excessive number opened by any application (none >100). I can browse all the disks (internal SSD, HDD, external USB brives, SD cards etc) without any problems evident. This has only started since I set up my iPhone to use iCloud to replicate contacts etc, and also the "Back to my Mac" function. I have since disabled this, disabled Google Drive, done a verify disk on the primary SSD, and the behaviour is still there. The only updates in that time have been to iTunes, which wirks as normal.
Anyone have any ideas?

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. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you boot, and again when you log in.
Note: If FileVault is enabled, 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 (not in safe mode) and verify that you still have the problem. Post the results of Steps 1 and 2.