If you experience a system crash during the installation of the Cisco VPN Client, uninstall and reinstall the software. To ensure there are no incompatibilities while uninstalling the VPN Client, use the appropriate method. For details, refer to the Uninstalling the VPN Client with the Uninstall Application section of Managing the VPN Client.
If this does not resolve the issue, use the manual method to uninstall. Refer to How to Manually Uninstall the Cisco VPN Client 3.5 for Windows 2000 .
If you are using an end-of-sale version of the VPN Client, refer to the release notes of the software version you are attempting to install in Cisco VPN Client: Versions and Options.
For more information, refer to Cisco VPN Client 3DES Cryptographic Software Download.
These are related Cisco bug IDs:
Upgrade or install
VPN - hardware & software clients
Crashes / reboots / traceback
Cisco VPN Client