[ID]ZE, if you are using ida v6.1 go to the folder "cfg" and open the file ida.cfg
search this string
Code:
//
// Location of Microsoft Debugging Engine Library (dbgeng.dll)
// This value is used by both the windmp (dump file loader) and the windbg
// debugger module. Please also refer to dbg_windbg.cfg
// (note: make sure there is a semicolon at the end)
//DBGTOOLS = "put here the full path of your windbg install folder";
, and change the DBGTOOLS path according with the windbg install folder...