The scenario is:
1) open just 3 primitive template based XAML files in XAML editor (without showing WPF designer even)
2) closeÃÂ two of opened xamlÃÂ files
3) Check intelliSense - it wouldn't work untill you restart VS.
If you open 2 XAML files -ÃÂ it works fine, butÃÂ 3ÃÂ -XAML - is enought for VS2008SP1 to fall down.
My XAMLs are following: