When installing ArcGIS Desktop or one of its service packs, the following error is encountered:
"Error 1904. Module C:\WINDOWS\system32\RegObj.dll failed to register. HRESULT -2147024770."
1904 errors can have many causes. The most common cause for this error appearing on module RegObj.dll is that an anti-virus program has removed the file.
Follow the steps in the "Windows Installer appears when starting ArcMap" article, located in the Related Information below, to eliminate this error.
If that does not fix the problem, follow the links in the Error 1904 Index, also linked below, for further suggestions.