[Rwp] Reaper and midi events not syncing to project

[Jes]

Okay guys, so I'm doing a lot with midi and a midi keyboard. I notice 
that when I have like twenty or so tracks, which my computer is more 
than capable of handling (IT is a custom-built daw), each track is out 
of sync with the others. I have to constantly move the items of each 
track to the right by pressing the 3 key on the numpad so that 
everything will be synced up, then after a while things start drifting 
apart again, and I have to split items up so I can sync them to the 
timeline again. Obviously this is rather annoying. Any ideas on how I 
can get things to stay synced up, so that I instantly hear samples when 
I hit a key, and so that I don't have to move items around on the 
timeline? I have been feverishly working on an album with guitars and 
drums and all that and don't have time for this inconvenience.