I had sent out a tweet on Friday to list #VS2010 about how my intellisense stopped working all of sudden in VS2010. Scott Guthrie @scottgu replied within 27 minutes and asked me to send a direct email to him.
I sent an email today. Within several hours I was redirected to Brittany Behrens @VSEditor.
Well here was the response that worked. I completely reset my settings.
The problem is that when ReSharper is enabled for a user, it disables the default Visual Studio IntelliSense and replaces it with ReSharper IntelliSense. The .vssettings file records that IntelliSense is disabled. When you install VS 2010, it automatically imports your settings file from the previous version of Visual Studio, including the setting that disables IntelliSense.
You can fix this in one of two ways:
1.) Install a build of ReSharper that’s compatible with VS 2010, or
2.) Re-enable IntelliSense in VS 2010. To do this, go to Tools->Options->Text Editor->[your language]->General and check “Auto list members”. For C#, you might also need to visit Tools->Options->Text Editor->C#->IntelliSense and reset those options as well.