Visual Studio 2012 is incompatible with windows server 2008 R2 error

I have Visual Studio 2012 installed insdie windows server 2008 r2 , and every thing use to work well, but today when i tried to open Visual studio 2012 i recevie the following message:-

    program compatibility assistant visual studio 2012 is incompatible with this version of windows

rogram compatibility assistant visual studio 2012 is incompatible with this version of windows

So is this a bug , or the message is correct, that i can not run VS2012 on Windows server 2008 R2 ? and why i use to work well with this ?