My goal is to have the com0com serial driver install without popping up the install wizard on both WinXP and Win2000.

I am working on WinXP x86. I have followed the test signing instructions for the com0com driver, replacing amd64 with i386 at line 60.

I have added my test certificate as both a root and trustedprovider using the following commands:

certmgr /add com0com.cer /r localMachine root
certmgr /add com0com.cer /r localMachine trustedprovider

And verified that it is listed under both locations.

I then run the newly built setup.exe. This installs the signed com0com.sys file into C:\WINDOWS\system32\DRIVERS and sets up a pair of virtual serial ports and a bus between them. Using explorer, I go to the DRIVERS directory, right click on the com0com.sys file and verify that it has the "test" digital signature. I then go into Device Manager, open the "com0com serial port emulators" entry, pick an entry and do Properties->Driver and see that it says "Not digitally signed". I click details for the driver and can see that it is referring to the com0com.sys driver file that I just confirmed is signed.

I found what might be a related issue but I'm not sure. Does WinXP demand a WHQL signature? If so, does that explain why the com0com.sys file is signed but the device driver entries say they aren't signed?