Sounds like the install failed at some point. Can you verify the following? Let me know if you need more info
- Check if “QuestSharedWebParts.wsp” exists in Central Admin -> Operation -> Solution Management list
- Check if this solution package is deployed successfully into the specified web application
- Check if the feature scoped at “Web” – the root web site administration Site Feature has “Quest Shared Web Parts for SharePoint” and is activated, if not, activate it.