Waveform sometimes not showing up when (lane) recording


I bought a new PC and had to re-install everything, so now I’m using Cubase 6.0.7 at the moment. Sometimes when I record, the waveform is not displayed, there’s just a flat line in the event. When I stop the recording, the waveform appears. But sometimes it doesn’t show what I can actually hear. And sometimes at first there is no waveform but then - still while recording - it starts slowly to appear at the beginning of the event, but the waveform is several seconds delayed to the sound.
In about 80% the waveform appears just while recording and shows the right signal, but in the rest of the cases the above described “error” appears.

It happens with old version project files as well as with completely new projects. Is this a known issue with Cubase 6.0.7?

My system: Intel Core i7-2600, 8GB RAM, Gigabyte B75M-D3V mainboard, RME Fireface 800, system disk is a 240GB SDD and recording disk is a RAID-1 system consisting of two 1TB-HDDs, Windows 7 Home Premium (64 Bit), Cubase 6.0.7 (64 Bit)

I’m not sure, but perhaps it only happens when using lane recording.

Here’s a screenshot:
waveform error.jpg
Edit: After a few more test runs I figured out that the error mostly occurs when doing a punch-in while lane-recording.