Well today, only a single day after installing Steam I have already run into the hung update problem
Our internet connection was dropped for some reason or other (commonly happens). The client wasn't in offline mode but it was still open and the menus could still be navigated. I quit the client and ran it again. This Update box appeared but obviously wasn't going to achieve anything with no internet connection so I pressed Cancel.
Pressing Cancel did nothing.
I tried right-clicking the taskbar icon so I could close it there. Nothing. When software has a UI that can become unresponsive like that, it may not be a huge bummer but it's a sign a system is not perfect.
After about a minute or 2 (didn't time exactly) it came up with Connection error and asked if I wanted to go into offline mode. I was starting to think more positively of Steam again for allowing me to do this.
So I press the button to go into offline mode.
Bam.
The upper window in the image was on top of the lower one.
I don't understand fully the meaning of why I got those two messages. The one underneath might have even been hanging there from earlier.
In any case, at this point the Steam client is running its process but there is no system tray and no taskbar.
I clicked ok on the upper box.
This made the lower box disappear. I checked Process Explorer and the Steam process had been completely unloaded (terminated).
Ok, maybe that was bad luck. Let's try again.
Exactly the same thing happened. This time I timed it and it took exactly 2 minutes before it realised the connection wasn't going to work and asked me about going into offline mode.
This is already a big problem. 2 minutes is a long time for a UI to be 100% unresponsive and useless to the user. From there, exactly the same as before happened.
So, I'm stuck with a dud internet connection for a couple of hours or so perhaps. I can't connect to Steam online so its update hangs. I can't cancel it without actually going into task manager and killing it manually. Most importantly, once it does determine the internet is down and offers me offline mode, it doesn't even work. If I wanted to play civ5 right now (assuming I had it!) I would be a sad customer.
One thing I would like to remind people who will perhaps be critical of this post is that I had no way in advance of knowing when my internet connection would drop, so "Put it in offline mode" is not really sufficient as a solution. If you do know a way to completely get around this problem though, please, I'd appreciate finding out.