When I try to compile old projects developed in Delphi 5, I get a message of
error immediately, stating that "Could not compile used unit
CommControls.pas" and Controls is highlighted in red.

The units Windows, Messages and SysUtils are not marked with a dotted red
line, while the rest, starting with Controls, Forms, Dialogs, Buttons and
ExtCtrls are marked as unknown packages.

In the setup following is declared:

Library path:
$(BDS)\lib;$(BDS)\Imports;c:\documents and settings\achriadm\my
documents\borland studio projects\bpl;C:\Program Files\Borland\Common
Files\LMD70SE\LIB\D10;c:\PROGRA~1\Borland\COMMON~1 \JEDI\jvcl\Resources;c:\PROGRA~1\Borland\COMMON~1\ JEDI\jvcl\lib\D10;C:\PROGRA~1\Borland\COMMON~1\JED I\jcl\lib\D10;C:\Program
Files\Borland\Common Files\JEDI\jvcl\dcu;C:\Program Files\Borland\Common
Files\JEDI\jcl\source\unix;C:\Program Files\Borland\Common
Files\JEDI\jcl\source\common;C:\Program Files\Borland\Common
Files\JEDI\jcl\source\vcl;C:\Program Files\Borland\Common
Files\JEDI\jcl\source\visclx;C:\Program Files\Borland\Common
Files\JEDI\jcl\source\windows;C:\Program Files\Borland\Common
Files\JEDI\jcl\source;C:\Program Files\Borland\Common
Files\SysTools\source;C:\Program
Files\Borland\BDS\4.0\source\Indy10\System;C:\Prog ram
Files\Borland\BDS\4.0\source\Indy10\Core;C:\Progra m
Files\Borland\BDS\4.0\source\Indy10\Protocols;C:\P rogram
Files\Borland\Common Files\ShellShock\source;C:\Program Files\Borland\Common
Files\FlashFiler\source;C:\Program Files\Borland\Common
Files\vPlanIt\source;C:\Program Files\Borland\Common
Files\orpheus\source;C:\Program Files\SciBit\MyComponents\D2006;C:\Program
Files\CoreLab\Bdp\MySql\BDS4

OutPut directory:
$(BDSPROJECTSDIR)\Bpl

DCP Output directory:
$(BDSPROJECTSDIR)\Bpl

And Browsing path:
$(BDS)\source\Win32\vcl;$(BDS)\source\Win32\rtl\co mmon;$(BDS)\source\Win32\rtl\sys;$(BDS)\source\Win 32\rtl\win;$(BDS)\source\Win32\WebSnap;$(BDS)\sour ce\ToolsAPI;$(BDS)\source\Win32\IBX;$(BDS)\source\ Win32\Internet;$(BDS)\source\Win32\Property
Editors;$(BDS)\source\Win32\soap;$(BDS)\source\win 32\xml;$(BDS)\source\Win32\db;$(BDS)\source\Win32\ Decision
Cube;C:\Program Files\Borland\Common Files\Maths3\DataStructs;C:\Program
Files\Borland\Common Files\Maths3\Maths;C:\Program Files\Borland\Common
Files\Maths3\Utils;C:\Program Files\Borland\Common
Files\XMLPartner\source;C:\Program Files\Borland\Common
Files\abbrevia\source;C:\Program Files\Borland\Common
Files\aPro\source;C:\Program Files\Borland\Common Files\EHS;C:\Program
Files\Borland\Common Files\Essentials\source;C:\Program Files\Borland\Common
Files\String_RFessources\source;C:\Program Files\Borland\Common
Files\Graphics32;C:\Program Files\Borland\Common
Files\Internet_Prof\source;C:\Program Files\Borland\Common
Files\LockBox\source;C:\Program Files\Borland\Common
Files\OfficePartner\source;C:\Program Files\Borland\Common
Files\OnGuard\source;C:\Program Files\NexusDB2\Delphi10;C:\Program
Files\NexusDB2Lite\Delphi10;c:\PROGRA~1\Borland\CO MMON~1\JEDI\jvcl\common;c:\PROGRA~1\Borland\COMMON ~1\JEDI\jvcl\run;C:\PROGRA~1\Borland\COMMON~1\JEDI \jcl\source\common;C:\PROGRA~1\Borland\COMMON~1\JE DI\jcl\source\windows;C:\PROGRA~1\Borland\COMMON~1 \JEDI\jcl\source\vcl;C:\PROGRA~1\Borland\COMMON~1\ JEDI\jcl\source\visclx

In project option Unit output directory is C:\wtest\ActiCalc32\dcu which has
been emptied.

When also trying to install Jedi projects, the BCC32 compiler complained
about the same error, cannot compile Could not compile used unit
'CommCtrl.pas'

As seen in browse path, source\win32\rtl\win is declared, and commctrl.pas
is present there.

Maybe a reason is within the PATH?

At moment it is:
PATH=C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\ ;C:\Program
Files\Borland\BDS\
4.0\Bin;C:\Program Files\Windows Resource
Kits\Tools\;C:\PROGRA~1\Borland\REMOTE
~1\6.0\Bin;C:\program
files\Inprise\vbroker\bin;C:\PROGRA~1\Borland\Delp hi5\Proj
ects\Bpl;C:\PROGRA~1\Borland\Delphi5\Bin;C:\WINDOW S\system32;C:\WINDOWS;C:\WINDO
WS\System32\Wbem;C:\PROGRA~1\F-Secure\Ssh\Program;C:\PROGRA~1\Borland\Delphi6\Bi
n;C:\PROGRA~1\Borland\Delphi6\Projects\Bpl;C:\Prog ram Files\Microsoft SQL
Server
\80\Tools\Binn\;C:\Program Files\Borland\StarTeam SDK 2005\Lib;C:\Program
Files\
Borland\StarTeam SDK 2005\Bin;C:\Program Files\SubVersion\Bin;C:\Program
Files\B
orland\StarTeam SDK 2005 R2\Lib;C:\Program Files\Borland\StarTeam SDK 2005
R2\Bi
n;C:\Program Files\MySQL\MySQL Server 4.1\bin;C:\Documents and
Settings\achriadm
\My Documents\Borland Studio Projects\Bpl;C:\Program
Files\PKWARE\PKZIPC\;C:\Pro
gram Files\EldoS\SecureBlackbox\Packages;C:\IBLOCAL\BIN ;;c:\SX;c:\Program
Files\
MySQL\bin;c:\progra~1\apache~1\Apache2\bin\;c:\cyg win\bin\

Anyone seeing the obvious error??