I'm using a 13" MBP with 10.7.2 installed, which is setup to sync calendar, address and bookmarks with iCloud. Since last week I've constantly encounter a problem that my Safari 5.1.1 would keep crashing, and I had to delete the ~/Library/Safari/extensions folder to get it back to work.
This situation happened whenever I've switch to wireless connection. In my office we've setup a limited wireless environment that all HTTP/HTTPS connections will be redirected through a proxy. Since last week the proxy server was malfunctioned. All HTTP connections are proceeded normally, but all HTTPS connections will be suspended. I'm not sure but I suspect it's the main reason for the crashing problem.
The syndromes are:
1. When I left Safari open, unplug the ethernet, and turn-on WiFi, everythings goes on normally, until I open an HTTPS web page, for example, https://www.icloud.com. Of course that HTTPS URL will not load, since our proxy is broken; but the connection itself will NOT timeout. I've tried to leave it connecting for 10 minuntes, and it's still there.
2. The statement above may due to a glitch in our proxy server and I can understand that. But the problem is: after I tried to open an HTTPS connection, the Safari will refuse to open any other URLs, including normal HTTP connections. It will just keep "connecting". Meanwhile the FireFox and Chrome can load these HTTP pages normally.
3. If I quit Safari in this situation, Safari will not be able to re-launce: the icon will keep bumping on the dock. I have to force quit Safari and delete extensions folder, so that it can be launched again. But even after Safari re-launced, it still refused to load HTTP pages.
4. Neither reconnecting WiFi, relogin, or switching back to ethernet can fix the problem. I have to restart the whole system to get it back to normal.
It seemed to me that some Safari-related process will keep in the system after Safari is quited. And that process may keep the inactivated HTTPS connections alive in its TCP pool, and blocked all sequence connections, including the iCloud synchronization. And while I force-quit Safari, the extensions.plist file is damaged. That's the only plausible explanation to this situation.
I'm sure this situation is introduced after 10.7.2: it's not the first time our proxy server breakdown, but I've never have this problem before.