.. you need to make sure you have the right pdb on microsoft website there is a debugging package(holding WinDbg and other debugging tools) which has a tool called SymChk which can be used to bring the right pdb files from microsoft website. the tool reads the version of your dll and exe files and tries to find the corresponding pdb for that version. C:\Program Files\Debugging Tools for Windows>symchk /r c:\WINDOWS\Microsoft.NET\Framework\v1.1.4322 /S srv*c:\dbg\symbols\*http://msdl.microsoft.com/download/symbols /r tells symchk to look in the 'c:\WINDOWS\Microsoft.NET\Framework\v1.1.4322' path and in all subdirectories in it /s Specifies the directories containing symbols c:\dbg\symbols\ is the location where the symbols are downloaded if you need a specific DLL file to get symbol for, you can use this (for ole32.dll for example) symchk c:\WINDOWS\system32\ole32.dll /S srv*c:\dbg\symbols\*http://msdl.microsoft.com/download/symbols Now, in WinDbg you can set in File menu the...