MIDI delay time comes suddenly

I swear I have never changed any setting of my Cubase 7.5.
Only one thing have done is moving a project from my Mac into my Windows system.
3 days ago I did everything well without any aware MIDI latency, even has driven with buffer size 1024.
However today, just now, an annoying delay time apeared when I’m working with my keyboard.
MIDI delay time comes suddenly.
It’s almost a 16th note delay following with my real hitting, no matter how short the buffer size of Audio interface I’ve set(even in 64).
I tried re-start the OS or re-set the Cubase, but the delay time is just there.
Does any one know what’s up with my Cubase?

There can be several reasons for that.
First things first: the project on mac or windows will perform the same on both OS’s on normal conditions in cubase.

What is different is the OS, and the drivers are different too.
This might be what is going on, but… since you write that it happens suddenly, i guess this has nothing to do with any softwarebut is rather a changed workflow.

Are you doing things differently now in the new project ?
f.e. using new effects or something like that ?

p.s. this kind of technical problems, it is Always better to give insight in what your system specs are, what type of drivers you are using, etc…

kind regards,