Hello!
I was making a sequence on Cubase 6.0.4 and suddenly every midi sequence shifted 7 semitones down, every single one, including drum tracks (which totally muted them).
The problem is that visually the notes are where they should be and I don’t really know what I did. I’ve double checked by manually transposing and listening.
I don’t usually transpose whole projects nor do I use the Transpose Track and I had to use it to keep working.
The transpose track affects drums too which is weird.
Any help would be appreciated! 
Is the project sample rate the same as the one set in your audio/midi interface?
If you click on a MIDI part to select it, what does the info line show in “transpose” section (you might need to enable it by right-clicking the info line and ticking “Transpose”)?
Do you have any midi inserts on your midi tracks?
Yeap, there it is. Thank you!
Isn’t it odd that I don’t remember having transposed the approx. 100 midi parts by exactly -7 semitones?
Could this be some sort of bug?
Also, why do midi parts follow note transpose when they should be GM? (They were setup as drum GM Map)
I remember, this happened to me a few days ago too, but I discarded that project, and if I remember correctly it only happened when I selected ALL the midi parts and moved them forward in the timeline. It was also the only moment I’ve ever selected all of the midi parts and the only moment something like that could have happened. I also think both times this has happened I had to move audio FX automation too with the midi parts together.
Thanks again! =)
Could it be that before recording or importing your midi parts you had the project root key set in the project window tool bar and then changed that setting occasionally?
Nope, never use those functions.
It actually happend in an instant. I was playing the song, shifted the sequences forward in time and then I noticed my drums were gone but the vst instrument was receiving midi data. I had to use the learn fuction to see where my notes had gone and it turns out my drum parts had transposed. I tried fixing those then I noticed my song was off key from what I remembered.
At most I used the mouse to move the sequence, nothing else. Might be some weird bug so I’ll try and replicate it. =D
But many thanks to you! 
Maybe there’s a keyboard shortcut for it you accidently hit?
I won’t deny this might be a posibility but I can’t remember having pressed anything but the mouse.
I’ll try to replicate the thing tomorrow.
Thank you. 