MIDI Keyboard Latency Issue in Logic Pro 9

When I play a note on my MIDI keyboard that is hooked up through USB, there is an audible delay before I hear the sound, regardless of if it's from a synth, piano, or anything. I've done a lot of research on this and none of the suggestions people give work for me. I've tried decreasing my I/O buffer size to 128, 64, and 32, none of which have helped. I've tried disabling and reenabling core audio, which didn't help. I've tried quitting and reloading logic multiple times, along with shutting down and rebooting my computer multiple times. This also just started happening in this one specific project yesterday, in my other projects I don't have this issue. I've tried deleting every single track in the project to see if it was a certain plug-in, but the issue still remains. I've had this problem in the past once or twice, but it just seemed to randomly solve itself and stop happening. I've also tried switching on and off every single audio and MIDI preference and setting available, still to no luck. Any help would be extremely appreciated!