1. Click on start==>run==>type "winword /s" without quotations and click ok.
2. Once Word is up in safe mode with the error message in front, hold down ctrl+shift+esc keys on your keyboard to bring the task manager up.
3. Click on the processes tab==>look for msiexec.exe (only the one next to your user name), click on it and end the process.
4. Excel should be running without an error message now==>close Excel in safe mode==>reopen it one more time in safe mode to check if it is opening with no error message.
5. Close winword /s and open word normally, it should work fine.