Window thread not working

[xandaz]

    Hi guys, I'm making this MDI app and wanted to put an initialization window with the various steps the app goes through while initializing. I chose to create a thread inside WinMain but when the window is created throws error 50. ERROR_NOT_SUPPORTED. What am i doing wrong? i'm posting no code because it has grown big an complex and i was hoping someone would givve ne a hand with this little intel.
   Thanks in advance.