I hope you only had one Captain Sim product installed. Your whole Captain Sim folder is deleted. Anyway....

Did you try an offline activation?

Try doing these to if that gets it working properly:
1) Turn your Antivirus software off while you install it. They can sometimes interfere because the activation needs to add the entry into the registry. I use Avast, and it sometimes blocks the installation, so I deactivate the "shields" for 10 minutes when installing FSX addons.

2) Turn off the UAC (User Account Control) because it is quite restrictive especially C:\Program Files or C:\Program Files (x86). It is highly recommended that you DO NOT install FSX in the default location if you are using Vista or Windows 7. You should install it in the root C: drive (C:\FSX) or on a separate drive or partition.

3) Run FSX using the "Run as administrator" option.