For applications built using Microsoft Platform SDK, Debug Symbols are written to an application PDB file when the application is built.
The Debugging Tools for Windows, an API used by the Visual Execution Debugger, uses these symbols to present meaningful information to Execution Analyzer controls.
These symbols can easily get out of date and cause aberrant behavior - the debugger might highlight the wrong line of code in the editor whilst at a breakpoint; it is therefore best to ensure the application is built prior to any debugging or recording session.
The debugger must inform the API how to reconcile addresses in the image being debugged; it does this by specifying a number of paths to the API that tell it where to look for PDB files.
For system DLLs (kernel32, mfc90ud) for which no debug symbols are found, the Call Stack shows some frames with module names and addresses only.
You can supplement the symbols translated by passing additional paths to the API; you pass additional symbol paths in a semi-colon separated list in the 'Debug' tab.