I think we've got these issues fixed in the upcoming v7.1 release.
There are two problems: one is that the profiler crashes if it tries to read static variable values when DEP is turned on and you have more than one appdomain. Office add-ins seem to be a particular cause of this problem. If you can temporarily disable DEP in your target application then you will avoid the issue. v7.1 detects DEP and disables the problematic code.
The second problem is partially caused by a .NET bug: if you have a class 'Foo' and you use it as a parameter to a generic (eg, 'IDictionary<Foo>') and then you unload the appdomain containing 'Foo', .NET does not report that the dependent generics are unloaded - in fact, I suspect it actually doesn't unload the generics at all, and leaks them, though I'm not completely sure on this. If you subsequently reload the Foo class into a new appdomain, the profiler thinks that the old generic is still around and sometimes tries to query information about it. v7.1 knows about this behaviour and will only look up generics whose parameters are in appdomains that haven't been unloaded.
The second issue can be worked around if you take a snapshot before the appdomain is unloaded (ANTS only reads class information once), or if you can force the problematic classes to load into a shared appdomain, or by avoiding behaviour that causes appdomains to unload (in nunit, turn on the 'use a single appdomain for all tests' option)
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