can anybody give a hint into what this BSOD (attached minidump) is caused by?
More minidumps are usually needed to be more definitive. In your case your error is 0x50: PAGE_FAULT_IN_NONPAGED_AREA but it only cited a core Windows driver which is too general. This error is defined as:
Requested data was not in memory. An invalid system memory address was referenced. Defective memory (including main memory, L2 RAM cache, video RAM) or incompatible software (including remote control and antivirus software) might cause this Stop message, as may other hardware problems (e.g., incorrect SCSI termination or a flawed PCI card). So...
1. Examine the “System” and “Application” logs in Event Viewer for other recent errors that might give further clues. To do this, launch EventVwr.msc from a Run box; or open “Administrative Tools” in the Control Panel then launch Event Viewer.
2. Run MemTest on your RAM for a minimum of 7 passes. Any errors and your bad stick(s) need to be replaced.