Just bought and installed Panzer General 2 on my laptop with Windows Vista, 64-bit, etc. and the game crashes when attempting to open game. Program must be closed immediately. I saw the support message on this site about the d3dx9_42.dll problem and deleted those files. Installed the June 2010 DirectX runtime package as advised, , installed (or tried to install) the DXSetup.exe as per "help" instructions and get an error message saying the installation could not be completed and telling me to check the DXERROR.log and the DirectX.log for reasons why it couldn't be installed. I
can't find these files on my computer. Just blew $9.99 on a game I really wanted to play and now it's useless and can't be played. This the first time I purchased a game from GOG and definitely the last time. Waste of money!

I have had the same problem. It isn't really gog's fault, newer Windowses have changed something in DirectX making it not backward compatible. Here is a solution I found somewhere on the 'Net and it works for me.

The game crashes at startup ('encountered a problem and needs to close')
Solution

First, go to Panzer General 2's folder and try launching PANZER2.EXE and, if that doesn't work, PG2UK220.exe directly.

If that doesn't help, delete the d3dx9_42.dll file. Then download and install the June 2010 DirectX runtime package. Some older games aren't compatible with the libraries included with current releases of DirectX and this package should help.
You will have to extract the files into a selected folder, then open that folder and launch the DXSETUP.exe file in order to proceed with the installation. Now try launching PANZER2.EXE and PG2UK220.exe.

Hope this helps

PS. Sorry for late reply