using server 2003 and 4.51: i only have the problem, when i use mercury with the help of a service-wrapper and connect to the console. then i can´t use the help. otherwise no problem.

The Help file doesn't appear when you choose it from the Mercury (4.51) Help menu under Windows 2003.

DEP is turned on except for Mercury,  Microsoft Help, and Windows WinHlp stub.

I assume that you are referring to Windows Server 2003. I am still running with Service Pack 1, so I cannot account for what installing Service Pack 2 may change.

When I open help on Mercury 4.51, I see mercury.exe and winhlp32.exe running under Task Manager. Can you see them under your installation?

SP2 running here.

Under Task Manager I can see mercury.exe but no winhlp32.exe .

Nothing relevant in the Event Viewer either. 

Hmmm I can't open up any help using the F1 key, only when pressing a help button or choosing Help/Contents... from the main menu.

Neither method works for me (menu or F1).

Can you open and read the help if you double click the help file in your mercury directory?