Latency when re-opening project (SOLVED)

[Badjools]

Just recently I have noticed that when I re-open some projects and try to record I get noticable latency where I had none before (I have ASIO installed). If I copy all the tracks into a new instance of Reaper the latency disappears until I open the project again so I am able to work around it, but it's not ideal as I lose other settings.
I have reinstalled both ASIO and Reaper to no avail. I might add it doesn't seem to happen with all projects, but I can see no link.
Any help or thoughts would be appreciated as it is becoming rather frustrating.

[Badjools]

I was trawling through some other threads concerning latency and I came across a comment at the end of one which said some plug-ins on the master channel can cause latency. Well I had a limiter on there and when I disabled it Bingo, no latency.