upper case characters in thread names

I just had a problem today in one of my test sites where I was calling a tcl proc that called an exec that was in system32.  It took down the site and I called support on it.

They said that there is a known problem with having upper case characters as part of the thread name on windows, especially in calling out to the operating system.

Has anyone else had this problem?  We have three sites running that have upper cases in the thread names.  

thanks,

Nancy