I have had the same problem, but on an almost continual basis. Every project I have started has as some point lost classes and the ability to add variables and event handlers. After looking through MS knowledge base I found and article about the classes disappearing. The resource is there, but the class is gone and hence, your ability to do anything with that resource. If you end VS and then find the .ncb (class view database) for the project that messed up and delete it, then everything will go back to normal. You can also find this information in MS knowledge base by scanning on .ncb. There is some register entry stuff in there, but my registry is fine. Just the stupid .ncb file keeps getting corrupted. The ideas I express here are not necessarily my own.