I recommend you to upgrade the application to the latest version compatible with your computer. First step is to uninstall the software using Add or Remove Programs feature:
If you use Windows XP or bellow you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the eToken PKI Client program and then click Remove.
If you have Windows Vista or above you need to go to Start > Control Panel > Programs > Programs and Features. Select the application and click on Uninstall.
After that, you can visit Software Informer review page of the product in order to obtain a link to the official download. Click the green Download button, save the file to your computer and install the application following the provided steps.