Try a Manual Offline Activation. This will require you to do a complete uninstall as per KB #685:

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KB #685:

Q: How to reinstall a product?

A: Quite a number of "issues" are caused by using of outdated version of a product. Prior to submitting a support request please make sure you have current version of a product.

To reinstall a product please perform the following steps in exact order:
Uninstall the product:
1. Go to Start> Programs> Captain Sim.
2. Select the product you wish to uninstall.
3. Click uninstall icon.

Install the product:
4. Make sure you have the latest version of the product
5. Run the product installer (the .exe file) and follow the prompts.
Please note: valid Order Number and Internet connection are required for installation/activation.

Please make sure you run the installation file as Administrator and that "User Account Control" is disabled (for Vista and Windows7), it limits admins ability to install programs.

If regular reinstall did not fix your problem you can try to clean registry.
Please be careful and do it on your own risk!

How to clean Registry:
1. Uninstall the product
2. Go to Start> Run. Type: regedit, click OK.
3. Find the product entry in HKEY_LOCAL_MACHINE\SOFTWARE\CaptainSim\ (please note, for Windows 64bit versions it is HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\CaptainSim\)
For example: HKEY_LOCAL_MACHINE\SOFTWARE\CaptainSim\C130XPRO
Make sure you are going to delete correct folder!
4. Delete the product entry folder.
5. Restart your computer.
6. Install the product.

If you stil have issues and the above does not help we must admit your system configuration is a rare exception. You can try to install the product on another system or request a refund.

From: General / Download/Installation (QID 685)