I was having an issue on my laptop where the Intellisense was broken when debugging C# code. It is working for VB.NET code. Here’s what it looks like for VB.NET when you start to type a variable name in the Watch window when in the debugger:
The problem is if I debug a C# project and try the same thing, I get nothing. No Intellisense even using the Ctrl-Space keyboard shorcut. Even the Immediate Window doesn’t work.
Since on my laptop I have ReSharper and a bunch of other add-ins installed, I chalked it up to some kind of conflict. But today, I just rebuilt a desktop workstation and put a clean install of Visual Studio 2008 Team System with SP1 and nothing else installed. Guess what… the problem still exists for me. Some Google searches also didn’t help. It doesn’t look like anyone else is having this issue, so I figured I better get a blog post about it in case you are in the same situation. I will update this post if I find a solution.
Please comment if you are having the same issue, or even better had the issue but found a fix! 
March 4, 2009 at 11:33 am
I am experiencing a similar issue. When coding a Script Component in an SSIS designer, I have full intellisense. When I create a different type of project in VSTS, I lose the intellisense for local variables. When I press ‘Ctrl+Space’, the editor simply adds a space; it does not toggle the intellisense popup.
This laptop does not have resharper installed on it.
March 4, 2009 at 11:54 am
This solution worked for me, but I can’t explain it:
I used the Import/Export settings option to import settings from “CurrentSettings”. Whatever was out-of-synch was fixed by that operation.
Typically, I like to understand the “why” behind an operation, but, these days, with everything that Microsoft breaks in each subsequent release, I’m finding myself in a place where I don’t really care anymore.
The feature sets in the Visual Studio and SQL Server IDEs are increasing but, the quality is definitely decreasing.
May 8, 2009 at 11:12 pm
I think you are on to something Danny. When I tried to do that, I actually got an error and wasn’t able to import any settings. Seems like there is just something wrong with my install. I will continue to limp along until 2010 I guess.
July 7, 2011 at 7:00 am
i am having the same problem,. please reply if you find any solution,.
January 13, 2012 at 6:25 am
Same problem it is working for VB but not for C#