The quality of your FireWire is nothing we have influence on. Fix it so that you see no errors counted up and the FF will work as expected.

This problem isn't limited to the FF 400.  I have a FF 800 and get this exact error right after updating to the latest 3.047 too.  The flashtool says I'm already using the 2.77 firmware, so this issue needs to be addressed.  I'm using Windows 7 (64-bit) too.  I'm unable to get to the FF settings window (by left-clicking on the orange system tray icon) so I can adjust the errors I'm getting - I hear dropouts when playing a simple MP3, and I can't even adjust it.  Instead, that popup comes up with the 2.77 firmware error.

Problem 1:
I kept getting intermittent errors on my FF400 and the bluescreen of death too. So I did a search and found a tool (http://www.thesycon.de/deu/latency_check.shtml) that reports your pc latency to see if there is any issues with my real-time audio streaming and bingo there was a very large red spike every five seconds which is not good.
I then followed the tool instructions on diagnosing which device is causing the red spikes.
Basically you have to go to the device manager and disable one driver at a time and see if the red spike stops appearing on the latency monitor.

I found that a network PCI card I had was causing this red spike and so I've removed the device and now I hardly ever hear glitches or see errors on my fireface when sequencing in my DAW.

Problem 2:
I had the 2.77 firmware version alert for my FF400 too which was strange but after removing all the drivers and re-installing them the message box disappeared. Make sure you remove all files when you uninstall the drivers so you get a clean install of the new drivers...

Hope this helps....
One thing I would like to find out is where the error log file is kept for the FF400?

I have the same problems/error message although I spent a lot of time finding out how to install and optimize my notebook for audio and especially FF400. I think I can say I tried almost everything, even an eCard with Texas Instruments FW from the recommended Dawicontrol. It works but very unstable.
So everybody is passing the buck to someone else. For me it's just frustrating because I'm a user and I have to work with this stuff and not spending days to configurate something that even doesn't work propperly in the end.

Thanks :-), but how I said, I optimized my notebook for audio. DPC shows latency about 100µs, maximum 188µs. So it's even possible to work with buffersize of 48 samples in Windows 7. I'm very glad about it. But then it happens sometimes (also with a bigger buffersize) that the connection to the FW400 get lost with the result of a buzz noise. Turning of-on/reconnecting doens't work. I only got this strange errormessage already mentioned. I also tried a different FW cable. Windows sounds are disabled and anyhow my onboard soundcard is standard for normal sounds.
I remember with my previews notebook it was possible to disconnect the FW cable while working in Cubase. Cubase was waiting until the cable was plugged in again and I could continue working. Was very stable...sadly not anymore no: