I have got the following problem with F# code recently: almost the complete code is underlines with curly red lines (indicating problems) and whenever I hover with the mouse cursor over any word the pop-up appears with the message “Unexpected token”. IntelliSence doesn’t work either.

Nonetheless if I start the project it is executed without any problem.
This happens both to already existing F# files and to newly created F# projects. I remember it was working just 2-3 months ago!
I tried to deactivate all possible extensions but it doesn’t help.
Any ideas?
I get this too. Sometimes, simply exiting and going back into VS helps. When I tweeted the problem, Don answered with this:
“do you have “python tools for visual studio alpha” installed? if so, uninstall it or apply the hot fix”
This wasn’t relevant to me (as I haven’t been anywhere near python) but I’m posting here in case it helps you.
— Edit: here’s a link to the patch, thanks to Alexander Galkin: http://pytools.codeplex.com/workitem/599