Dilip,
thanks a lot for tip. I have uninstalled GSS 2.5.1 from my notebook and investigated a bit what remained in the registry. In my case uninstall has removed all installation information, so I did not apply solution from support case you have recommended.
However I have found that there is a key in registry HKEY_CURRENT_USER\Software\Symantec\Symantec Ghost\Ghost Boot Wizard\WinpeLastLocation which points to location of WinPE. In my case this key pointed to disk F: where I had GSS 2.5 installed some time ago. This key was not removed during GSS 2.5 uninstall, nor during GSS 2.5.1 install/uninstall. So I have removed it and installed GSS 2.5.1. Now it works!
I don't have disk F: attached to my notebook anymore. When I have applied solution from
http://www.symantec.com/connect/blogs/rollback-corrupt-winpe, GSS has used file copied to C:\Users\All Users\Symantec\Ghost\Template\common\winpe\sources in order to recreate boot.wim in winpe\sources and winpe-512\sources during GSS start, however looked for wim files in disk f: during ghost CD image creation, and because disk f: was not present, displayed an error.
MaFe