Delphi context help says "Cannot find the C:Program FilesBorlandDelphi7Helpd7.hlp file"

My Delphi 7 installation started giving this error. The error message shows the correct help path, but with the backslashes removed. The Help files are pr开发者_运维百科esent in the expected location (C:\Program Files\Borland\Delphi7\Help). I'm running D7 under Windows 7. It was working previously.

Sometimes I also get this error :

I have searched on Google, and I find others reported the problem, but no solution has been posted.

I have found that this error can be cause by help files missing from OpenHelp project.
To replicate error I would just add {$WARN} to simple project and press F1 on WARN word.
To fix it:

• run delphi 7
• click Help->Customize (OpenHelp window will be shown)
• in OpenHelp for each of "Context", "Index" and "Link" tabs:
  
  • select tab
  • browse to C:\program files\borland\delphi7\help (or whatever your delphi installation path is)
  • select missing files (in my case it was d7dopts.toc, d7dopts.hlp, d7derrs.toc and d7derrs.hlp)
  • save project