This hotfix addresses issues with debugging on Windows 7. you can found more info in this site.

This hotfix addresses issues with debugging on Windows 7, including:

• Assertion failure: “(!SetThreadContext failed”)”
• On Windows 7, running under the debugger can cause the debugger to crash on shutdown.
• No Wait Chain is shown on Windows 7

Internal Tracking Number(s): QC 74732, QC 78575, 271589