c# - visual studio intellisense doesn't work anymore -

i'm developing visual studio 2013 update 4, resharper , xamarin , since few days have strange behaviour. visual studio tells me everytime entered code wrong , intellisens doesn't work anymore. happens since crash of visual studio.

visual studio marks me in red , if @ tooltip, shows: "module 'system.runtime, version=4.0.0.0, culture=neutral, publickeytoken=b03f5f7f12d51a3b' should referenced"

if remove .suo file, works until project closed , reopened again.

does has idea on solving it?

thanks.

i think reinstalling visual studio solve problem.

otherwise problem should addressed visual studio support , not so