We have been getting some cases in which AutoCAD 2015 would not launch. The error is:

The application was unable to start correctly (0xc0000142). Click OK to close the application.
To solve this problem, we needed to use an advanced Windows Sysinternals Tool called Autoruns for Windows:
http://technet.microsoft.com/en-ca/sysinternals/bb963902.aspx
Launch the program and look for the following tab: AppInit. This will basically tell you if a dll is unsigned or digitally no longer valid on your computer. All you have to do is rename each dll listed, one at a time and launch the product to determine the problematic dll.

With a bit of serendippity, we [Avto Chachava] also solved a (0xc0000005) error using the same process, in this case the problematic dll was:
nvinitx.dll
We have been using Procmon for ages, here is another tool in our troubleshooting arsenal. Thanks to Kenny Chan for sharing this tip with the community.
http://upandready.typepad.com/up_and_ready/2011/10/general-systems-the-basics-of-using-process-monitor.html
Reference
http://en.wikipedia.org/wiki/DLL_injection
http://en.wikipedia.org/wiki/Digital_signature
http://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/The-application-was-unable-to-start-correctly-0xc0000142.html
Epilogue
This appears to be an issue with Adobe Acrobat 9.5.x Extended Web Capture module and this can be easily seen in AppInit tab of Autoruns for Windows.

http://forums.autodesk.com/t5/Installation-Licensing/AutoCAD-2015-0xc0000142-Error-occured/m-p/4923686/highlight/false#M84203
Epilogue II
Below is another vendor that has an unsigned dll.

Epilogue III
One of our technical gurus [Osamu Motoyama] was able to change a setting in the registry to solve this problem. You can try to change the value to default of 0 in the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\LoadAppInit_DLLs

FYI, some of the offending 3rd party applications may change this value to 1 upon launching them.
Epilogue IV

Kaspersky 2011 AV is another problematic Appinit.
Reference
http://msdn.microsoft.com/library/dd744762%28v=vs.85%29.aspx