On a Windows 7 with SP1, all patches and updates, Visual Studio installed, Dell PC 12GB 64-bit Intel i5-2400CPU, installed runtime and developer tools, demos, etc. things run fine. After reboot, a popup states "OVRService_x64.exe cannot start, missing file dbghelp.dll" which is a windows system file. Reboots and re-install of oculus and a windows repair did nothing to help.
Some sites refer to 'corrupt' windows files after software installs and proposed a way to fix it. I tried this, and now all seems to be working fine. The fix is as follows;
1. Run CMD as administrator (search CMD, right click and Run as Administrator)
2. type sfc/csannow
WARNING: This takes some time, mine ran over 10 hours. It checks every windows file. On my system, about 5 hours in this utility repaired the corrupt file dbghelp.dll... now the OVRService_x64.exe runs without complaints.
NOTE: The utility produces a log in C:\Windows\Logs\CBS directory named CBS.log --> You need to run NotePad (or any editor) as Administrator to read the log file.
Hope this helps - AndyZ