I've downloaded Lightroom 4 but I get an application error message (0xc000007b). Please help
See this Adobe Knowledge-Base article:
Moving this discussion to the Photoshop Lightroom forum. LesKamae you may want to try the steps listed in Error "Unable to start correctly - 0Xc00007b" - http://helpx.adobe.com/lightroom/kb/error-unable-start-correctly-0xc00 007b.html.
Did you by any chance download and install called "iLivid".
There are a lot of threads a few months ago indicating users had used this program then getting this error message when trying to install Lightroom. Copying the missing files should cure the problem.