It is a bit puzzling that deleting or renaming a single (in my case empty) folder helps, but it really does. I wrote the simplest possible CMD script for it so that it is as convenient as possible for you. So open the Command Line as administrator and run this command:
rename "C:\Users\Radeksunamo\AppData\Roaming\Microsoft\VisualStudio\10.0" "10.0_OLD" from any folder; the program will find the right folder on its own. Ever since I renamed this folder, I no longer have to close the project every few minutes and start it again, because IntelliSense no longer turns off.