Sorry to hear that you had to uninstall JustCode. We will be happy to hear from you what was missing or if you had any particular problems with the tool. This way we could make it better and if you try to give it another shot in the future have what you were missing.
Addressing the issue at hand, you can enable VS error reporting from Tools -> Options -> Text Editor -> C# -> Advanced. There you can find two options - "Underline errors in the editor" and "Show live semantic errors". Checking those should solve you issue. JustCode disables those in order to not mix up with its own error underlinings.
Sorry again for any inconvenience that our software may have cause you.
the Telerik team