To help assure a successful installation of the SOLIDWORKS® software, the Installation Manager checks to see if there are any pending reboot requests on your system. A pending reboot request occurs when a program or installation makes a change to files, registry keys, services, or operating system settings. This leaves the system in a transient state.
For example, a SQL Express installation automatically terminates if a pending reboot request exists. In other cases, the transient state of a SOLIDWORKS installation can lead to installation errors.
As a best practice, restart your system before beginning a SOLIDWORKS installation. If it is not possible to restart the computer at the time of install, then you can ignore the warning. In such cases, restarting the system becomes the first troubleshooting step following an unsuccessful installation