While try to browse SharePoint Portal site get an error "Cannot connect to the configuration database"

When you try to view your Microsoft SharePoint Portal Server 2003 Web site, you receive the following error message:

"Cannot connect to the configuration database"

This behavior occurs for many reasons. I have mentioned the workaround for one of the reason where the issue was with MDAC 2.8 SP2 installation broken

We created a UDL file to check the connectivity between SharePoint Portal server and SQL server

When we run the UDL file we get an error RUNdll32.exe "The procedure entry point SystemParametersInfoI could not be located in the dynamic link library MSDART.DLL."

When we click ok we get an error "Error loading C:\PROGRA~1\COMMON~1\System\OLEDB~1\oledb32.dll The specified procedure could not be found."

Check for the version of the MSDART.DLL files in the following location

%windir%\System32

%windir%\System32\Dllcache

%windir%\ServicePackFiles

If you find differences in the file versions then run the below command which is explained in https://support.microsoft.com/kb/889114

C:\> copy %windir%\system32\dllcache\msdart.dll %windir%\system32

Choose Yes

Now try to run the UDL file, if it fails again

Then run the component checker against MDAC 2.8 SP2

Click on the link for MDAC Utility: Component Checker

You will find couple of files missing 

To fix the missing files 

Browse to C:\windows\inf folder in windows explorer,

Right-click on mdac.inf and select Install,

Then when prompted for i386 places go first to C:\windows\servicepacks, and then if files still can't be found, point to your CD or C:\i386 folder.

Finish the installation

Do an IISreset

You will be able to run UDL without any error

Now you should be able to browse the SharePoint Portal Server 2003 sites