That did the trick. For the record:
1) Used msconfig to switch to safe mode boot
2) Booted to safe mode
3) ran cmd.exe as an administrator
4) typed "cd C:\Windows\System32\LogFiles\WMI"
5) typed "rename RtBackup RtBackup2"
6) Used msconfig to switch to normal boot mode
7) Reboot and found event viewer working