This happens for me too, and I think I have some further information that may prove useful.

I used to use only one tag, "Today", so that I effectively had a short list of things to do now-ish. Recently, I moved a bunch of tasks from my gmail tasks list into Astrid, creating many more tags in the process. It was around this point that I began to notice the problem that everybody has described above (simply "launch astrid, note that it just says 'loading...' for ever, but you can still view by individual tags"). At this point I assumed the bug was somehow related to having either lots of tags (I have about 10 now) or lots of tasks (I have about 30).

But recently I noticed something interesting that may shed some light on the bug: I said above that I can (like most people who've spoken here) view my tasks by individual tag without a problem. I realise now that I can do this for all but one tag, my tag called "Today". Now that I notice this I can recall adding a new task to the "Today" tag (from within the "Today" view, so it automatically got the "Today" tag) and it didn't seem to appear in the list afterwards, and when I went hunting for the new item I couldn't find it in the main list either (because the main list would just say "Loading...", but I can't be certain that this was the first time this occurred).

So, my theory is, that something may be going wrong in the adding of a new task, whether it be tagged or not, and when you go to view the list of tasks (either all tags, or just the list of tasks tagged with the same tag as the problem one you tried to create), you'll get the "Loading..." freeze.

Here is the output from "logcat" for me:

--- snippet begin
I/ActivityManager( 1056): Displayed activity com.timsu.astrid/.activities.TaskList: 1629 ms
E/astrid  (15716): Error loading task list
E/astrid  (15716): java.lang.NullPointerException
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity.fillData(TaskListSubActivity.java:605)
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity.access$5(TaskListSubActivity.java:533)
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity$2.run(TaskListSubActivity.java:244)
E/astrid  (15716): 	at java.lang.Thread.run(Thread.java:1058)
D/InetAddress(15716): data.flurry.com: 63.150.3.196 (family 2, proto 6)
D/LocationMasfClient( 1056): getNetworkLocation(): Returning cache location with accuracy 514.0
D/LocationManager(15716): removeUpdates: listener = com.flurry.android.FlurryAgent@4337ae50
I/Resources(15716): Loaded time zone names for en_US in 1769ms.
E/Astrid  (15716): Alarm (112, 16) set for Wed Nov 18 21:00:25 GMT 2009
D/dalvikvm(15716): GC freed 8937 objects / 445256 bytes in 128ms
I/Resources(15716): Loaded time zone names for en_US in 1122ms.
E/Astrid  (15716): Alarm (112, 16) set for Wed Nov 18 21:00:25 GMT 2009
D/FlurryAgent(15716): Report successful
--- snippet end

and here's the logcat result for me going into the "Today" tag's task list:
---
E/astrid  (15716): Error loading task list
E/astrid  (15716): java.lang.NullPointerException
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity.fillData(TaskListSubActivity.java:605)
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity.access$5(TaskListSubActivity.java:533)
E/astrid  (15716): 	at com.timsu.astrid.activities.TaskListSubActivity$2.run(TaskListSubActivity.java:244)
E/astrid  (15716): 	at java.lang.Thread.run(Thread.java:1058)
---

if i go into the task list for a tag that doesn't cause this freeze then i don't get any error output.

I'm running Astrid 2.10 on a Samsung Galaxy with firmware 1.5.

I hope this helps!