http://blogs.msdn.com/junfeng/archive/2008/04/07/a-case-study-of-a-nullreferenceexception.aspxWe are seeing a NullReferenceException in our stress program. The investigation process may be helpful to some folks. Thread 22 is showing a Watson dialog. This is a register corruption. 0:022&gt; kp ChildEBP RetAddr 091bc9a0 76961220 ntdll!ZwWaitForSingleObject(void)+0x15en-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/junfeng/archive/2008/04/07/a-case-study-of-a-nullreferenceexception.aspx#8365976Mon, 07 Apr 2008 20:41:04 GMT91d46819-8472-40ad-a661-2c78acb4018c:8365976Rich<p>How does a register corruption happen? &nbsp;Is it only in the CLR? &nbsp;Or can an app cause it?</p> http://blogs.msdn.com/junfeng/archive/2008/04/07/a-case-study-of-a-nullreferenceexception.aspx#8367079Tue, 08 Apr 2008 03:40:32 GMT91d46819-8472-40ad-a661-2c78acb4018c:8367079Norman Diamond<p>06b2d7e3 e810a078f9 &nbsp; &nbsp; &nbsp;call &nbsp; &nbsp;mscorlib!System.Collections.Generic.EqualityComparer`1[[System.__Canon, mscorlib]].get_Default() (002b77f8)</p> <p>06b2d7e8 8945f0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;mov &nbsp; &nbsp; dword ptr [ebp-10h],eax</p> <p>06b2d7eb 85f6 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;test &nbsp; &nbsp;esi,esi</p> <p>Does get_Default() report a result by setting esi to 1?</p> http://blogs.msdn.com/junfeng/archive/2008/04/07/a-case-study-of-a-nullreferenceexception.aspx#8368007Tue, 08 Apr 2008 10:01:12 GMT91d46819-8472-40ad-a661-2c78acb4018c:8368007junfeng<p>Rich,</p> <p>register corruption happens because the register is overwrited. This could happen for a couple of reasons, for example, the registers are not correctly saved and restored on method call, C++ functions modify register directly using __asm syntax, or, CPU hardware problem, like overheating. CLR could be one of the cause.</p> <p>Norman,</p> <p>The return value of call is stored in eax in x86, and rax in x64. It should not modify esi.</p>