Logic Pro 8 Midi issue Sync

I constantly get a Can't sync Midi and Audio message in the middle of sessions. Everything is current. Is this me or is there a fix?
I usually get this alert when there's too much stuff in RAM.
What's the memory of your mac?
If you use Activity Monitor, do you see a lot of Disk Activity?

have you tried increasing the buffer size?
Thanks Peter. I have 4G and run nothing but Logic when working. Also cold shut down to clear RAM prior to. Sometimes disk is busy sometimes not. I will try the buffer size and see what happens. Thanks for this.