run a powershell script on every user login/unlock

Hi everybody

I need to run a powershell (that opens an interactive dialog box) when every user log in or unlock session or remote connection to this server.  In other words it have to be run every time a user enters a credential. 

I tried task scheduler, but it didn't work properly. I tried triggers like "on workstation unlock" and "on connection to user session". I change user and group to administrators but still it runs under the author user (me) . 

I found out user login event id is 4801 and 4778. can I use these event ids to run powershell code? Can I check raising the event ids through my code? 

any other idea please?

Thanks in advance