Runtime error 217 can occur due to incorrectly registered DLL files, outdated system files like Msvcrt.dll, incorrect date/time settings, missing files like Stdole32.dll, virus infections, outdated device drivers, invalid registry entries, or a fragmented hard disk. The document provides steps to fix each potential cause, including reinstalling applications, updating system files, adjusting date/time settings, scanning for viruses, updating device drivers, cleaning the registry, and defragmenting disks.