I had uninstalled some CTP "Community Technology Preview" software. The next thing I know I'm getting this "SignTool" error when trying to publish with ClickOnce in Visual Studio 2005. It wasn't a hard fix.
- Download the latest CAPICOM "Platform SDK Redistributable" here.
- Run the downloaded "capicom_dc_sdk.msi" file.
- I had to register the DLL file. Assuming the installation directory is the same just run the following command from the command prompt.
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\CAPICOM\CapiCom.dll"
Hope this helps!