Trouble winch standalone plugin

Hi,
I just get an MPC Live 2 yesterday.
I have troubles with the 3 standalone plugins : BassLine, electric instrument and tubesynth.
I have seen they should be run in the standalone mode. But if I can select them on the Programs setting and access to the settings of the instrument, the sound is awful, totally dirty and with a strange tremolo effect. It is quite like if the ram wasn’t enough to run the instrument properly. Anyway, it is impossible using it in a production.
On the other side The sound is clean if I use the MPC software and the MPC hardware as a controller. But for sure, in this case the sound come from the computer and not from the mpc...
Any idea about the reason Of the trouble and a possible issue ?
Thanks.

Ok I've found the issue. The problem came from the Pad Parform. The fundamental note was on C-2. Changing this to C1 solved totaly the problem and the sound of the plugins is now perfect