hwProfileInfo.szHwProfileGuid is an array of TCHARs, not a std::string. TCHAR does not have a c_str() function.
PLEASE USE CODE TAGS (the <> formatting button) when posting code.
It makes it easier to read your code and also easier to respond to your post. http://www.cplusplus.com/articles/jEywvCM9/
Looks like you tried to use code tags, but the opening tag needs to be lower case.