Running the 2-23 nightly for Win32 (the last version that doesn't crash on start with a library error), I get Qt Creator to crash every time I try to put an underscore in a new external tool category. I haven't tried any other special characters. Here's the crash dialog:

---------------------------
Microsoft Visual C++ Runtime Library
---------------------------
Runtime Error!

Program: C:\Qt\qtcreator-2.1.81\bin\qtcreator.exe

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

---------------------------
OK
---------------------------