The most likely cause of this is a virus scanner or other security program interfering with vorpX.
There are a few other kinds of programs that may also interfere with vorpX, but if it refuses to start completely, an av program seems to be the most likely candidate.
The trouble shooting guide in the help has a few more details on this.
Please also try to reinstall vorpX and the Oculus runtime 0.5.0.1 after uninstalling both and rebooting. Just to make sure it’s not simply an issue with some corrupt file(s).
If you can’t solve the issue, please send a mail with your system specs and a list of your running processes (or a screenshot of your task manager showing them) to support |at| vorpx com. A dxdiag.txt may also be useful (can be created with dxdiag, which is part of Windows).