Thanks for using Apple Support Communities. It sounds like reinstalling Bonjour might help with this. This article contains instructions for that:
Uninstall and reinstall
If none of the items described above are present after you've installed Bonjour, try uninstalling and reinstalling the software.
- Go to the Control Panel and click on Add or Remove Programs.
- Select Bonjour from the list.
- Click Change/Remove.
- Choose Remove, then follow the onscreen instructions.
- Reinstall Bonjour for Windows from the Apple website, or the media on which it was supplied to you.