You all should use the search function first. There are several posts about this problem already since yesterday. Give the devs some time to fix the issues and try again later.
Bei mir hat die Neuinstallation des C++ Redistributables Package geholfen: http://download.microsoft.com/download/8/4/A/84A35BF1-DAFE-4AE8-82AF-AD2AE20B6B14/directx_Jun2010_redist.exe
Edit:
Info aus folgendem Forum-Beitrag: