From: Theodor Willax
How could I debug this error?
You can use the map files to find out where things went wrong. On the BSOD you attached you can find that the kernel crashed at <win32k.sys: 142f8>. So you can go to subsys/win32k/win32k.map and find (relative) address 142f8. If you compiled with DBG := 1 in your config file this should give you the exact source line where the crash occurred.
If you need a stack backtrace, use the values on the "Frames:" line in the same way.
Gé van Geldorp.