There can be an issue with the intellisense .ncb file. If the no compile browser (.ncb) file located at the root of your project directory is read-only or becomes corrupt in some manner, IntelliSense information will no longer be available. To fix this, do the following:

Close the solution.
Delete the .ncb file.
Reopen the solution. Reopening the solution creates a new .ncb file.

USEFUL?
We benefit hugely from resources on the web so we decided we should try and give back some of our knowledge and resources to the community by opening up many of our company’s internal notes and libraries through mini sites like this. We hope you find the site helpful.
Please feel free to comment if you can add help to this page or point out issues and solutions you have found, but please note that we do not provide support on this site. If you need help with a problem please use one of the many online forums.