An Unofficial RAD Studio 2007 Debugger Fix for Windows 7 has been published.

The primary problem being fixed is a debugger assert that usually occurs when terminating a process being debugged on a 64-bit version of Windows 7.

The text of the assert is:
Assertion failure: “(!”SetThreadContext failed”)”
This version also fixes a few minor problems when debugging on Windows 7.

you can download this patch from this site