It's a common issue that IDLE cannot start on Windows because

"IDLE's subprocess didn't make connection.Either IDLE can't start a subprocess or personal firewall software is blocking the connection."

Everyone claim that the user should set the firewal so that IDLE can connect to subprocess via loopback. I found, instead, that this issue is often caused by an incorrect or missing setting of one the following variables: HOME, USERPROFILE or the combination of HOMEPATH and HOMEDRIVE; if these variables don't represent an existent and writable directory, the error occurs.
Try setting HOMEPATH to an unexistent  or unwritable directory just before launching idle.bat script.
Check IdleConf.GetUserCfgDir() in module configHandler.py, where the function os.path.expanduser is called to get the user home directory. You might also temporarly patch GetUserCfgDir, setting the userDir variable to an unexistent path just after it has been initialized via os.path.expanduser (line 202).
Should be considered a check on expanduser behaviour?

OS: Windows XP
Python version: 3.2.2

clikkeb