Unknown Publisher issue on XP Pro

I have recently reinstalled XP Pro on my laptop and now every time I try to start Notify or the GroupWise client I get an Open File - Security Warning - The publisher could not be verified, Unknown Publisher.

This has never happened to me in the past, and no other application I have installed is showing this issue every time I start it.

Also, I asked the installer to do a Workstation install, but it is running the programs from the installation directory and not the C: drive.

Does anyone have any ideas on how I can resolve this issue?

I have tried downloading the latest GroupWise 6.5 client, but the problems persist.

Thanks,
Rob