PSP Mix Pack plug in delay in FL Studio 5

Recently i brought PSP's mix pack plug ins. For about a month i've loaded em up in me mixer channels with no problems but now there's a delay with the sound as soon as i load up a psp mix pack plugin.

For example if i'm runnin a bassline through channel 2 on me mixer and load up a plug in that channel, the bassline will now b slightly out of time with the rest of my song.
This is only occuring with the mix pack plugins. Any help would b appreciated :)
sash