I just received a Akai MPD24, and everything worked fine. But first Hypersonic 2 gave a "settings not loaded" error (I think because I moved from Vista to Windows 7), and now FL Studio itself is starting to bug too.
I never used FPC before, but I'm using it now since I've got my MPD24. Since I started using the FPC, the errors started to popup too.
The error that mostly pops up is this one:

After I pressed OK I still can press buttons in FL, but they don't react. This error pops up when I'm clicking on the playlist.
I'm getting the "FLP file is corrupted" error too, but when I quit FL Studio via Task Manager I still can open that FLP.
Maybe it's helpfull to say that I have a MIDI-Keyboard too which is connected.
My setup:
Windows 7 Ultimate 64bit
Q9400 3.2Ghz processor
5GB RAM
EMU 0404 soundcard