problems with trills: missing notes

Hello everyone,

I must say I am truely amazed by Pianoteq, no question. Now there is just a little issue that I'd like to resolve...

while playing fast passages i notice that notes are being missed. especially during trills this can become painfully apparent.

i am using a lenovo thinkpad z60t with a 2GHz Pentium M on WinXP SP2 and a USB Tascam US 144 audio device.
the masterkeyboard doepfer lmk2+ is usb powered via a hub and feeds the midi signal into a separate usb port on my computer. I am running the standalone version, no sequencer.

other standalone instruments like the Native Instr. FM7 work fine using the same buffer settings on my soundcard.

I tried with all available buffer settings - same problem. I noticed that the C3 instrument is more prone to losing notes than the M3 or older Pianoteq instruments.

the observed CPU load is always totally low...meaning that there should be sufficient resources on my setup. I am stumped.

Can anyone give me some advice on this?

thanks for your support,

bOb