A: 

Have you ruled out the d'oh options of maybe hitting a breakpoint on an accessor property (possibly in a different thread) for this.bndLocation.DataSource?

Martijn
Would that also freeze the whole VS2008? Honestly, I cannot think of ANYTHING that would freeze Studio itself.
Vilx-
Er, no, this shouldn't render Visual Studio unresponsive
Martijn
See update, maybe you get an idea.
Vilx-
A: 

I don't know what your problem is, but I can point out some things that you are doing which could be causing problems:

  1. Access to modified closure within lambda expression:

You should not access "usr" within a lambda expression since it is a closure within the foreach loop, and you can get some really weird behavior here. (the value of "usr" will be taken as the last one instead of the one it was created with.

It doesn't seem to me that this would be your problem. To see if it is, do this:

var usrTemp = usr;
Found = new List<Business.Location>(this._AllLocations.Where((a, b) => a.Distributor == usrTemp.Distributor));
  1. I don't know what kind of LINQ provider you are using, or what your OnItemBound events look like, but in the first example you are biding your items when you still have an iterator open on _AllUsers. If your business layer isn't written as to support this concurrent access, this might be causing a problem.

To see if this is a problem change the foreach loop:

foreach (var usr in this._AllUsers.ToArray())
tster
That's why I'm creating a `List<T>`. It enumerates through the contents right there and then and makes a copy of the enumerable. `usr` isn't touched after that. Also, `_AllUsers` and `_AllLocations` are simple generic `List<T>`s. `_NoLocations` is an empty array.
Vilx-
1. The closure doesn’t escape the loop, so that is clearly not the problem. 2. The code never binds `_AllUsers`, so having the iterator makes no difference.
Timwi
@Timwi, unless you have access to Telerik's source code, you can't know that setting DataSource doesn't do anything.
tster
@tster: The code posted in the question does not pass a reference to the list into Telerik (not even indirectly), so it doesn’t matter what Telerik does.
Timwi
See update, maybe you get an idea.
Vilx-