How to fix error "Cannot connect to the configuration database"

When you try to view your Microsoft Windows SharePoint Services 2.0 Web site, you receive the following error message: Cannot connect to the configuration database.

Please read this KB to know how to fix this error: http://support.microsoft.com/kb/823287

On that KB, Microsoft explains 4 situations may happen that error and lead to verify on your system. But another reason was found and often causes if you are running on SharePoint Farm or using Domain account to configure out the SharePoint.

1) On SharePoint Farm

You should check on your server in which hosting SharePoint Central Admin the Local Users & Groups to find out whether any account did not deduce to fullname account. That means each of account in Local Users & Groups must be show full name of that account and you will see them very clearly. 

For example: when you get the error "cannot connect to the configuration database", let do the following instruction. 

-> from Start Menu -> Run -> type compmgmt.msc then Enter. After windows opens, expand Local Users & Group, click to open Groups, and then double-click on any group. You will see the error like that:

Because the domain account did not deduce on your system, so SharePoint can not connect to SQL server and that error happens.

For double-hop, you should verify this thing both on SQL machine where is hosting your SQL and SharePoint Central Admin.

Note: Don't try to remove that account and re-add them.

To fix this issue, just disconnect both your system from your domain and join to the domain again.

2) On Single Server using Internal DataBase (connect to MICROSOFT##SSEE)

If on single server happens this issue, please remove the account to connect to SQL group in Local Users & Groups. Find in all SQL groups and WSS/MOSS group and remove that account out of group, then add this account into that group again.

Good luck.