[Qt-creator] QtCreator 2.4.1 on Win64 can't execute batch scipt in Custom Build Step anymore

[Philipp Münzel]

I have a problem with my builds since I upgraded to Qt-Creator 2.4.1 on Windows 7 32bit.

Before, using QtCreator 2.2, my build process had a "custom process step" after make, which executed a batch script by calling cmd.exe with the arguments /c myscript.bat

Since I upgraded to 2.4.1, the custom build step fails with 
"The syntax of the command is incorrect.
01:06:58: The process "C:\Windows\system32\cmd.exe" exited with code 1."

When I invoke the same command from a cmd window, it works flawlessly. So it must be an error in QtCreator spawning the cmd.exe. 

I tried deleting my .pro.user file and setting up the custom build step again to no avail.

Any ideas?

Regards,
Philipp