I looked at your dump files. Familiar pattern....
Version 1.3.4 Windows has an intermittent memory corruption problem under heavy AIS/GPS load with external port mux like Franson. The error appears on memory free(), so the first indication of the problem occurs long after the fact.
Working hard to track it down. Have enabled Pierre (not regular forum member) with debug version of opencpn
to try to get to the root cause. Blubaju crashes too, same root. Common thread seems to be complex port configuration, with external mux like Franson, and another app like GPSMON.
This debug version of opencpn checks the entire crt heap every second, looking for corruption. Obviously slows down the application.
I cannot reproduce the failure locally. Tried and tried.....
If you are willing, you could try the same type of debug test:
So, to proceed:
1. Download the Microsoft debugging tools from
Install Debugging Tools for Windows 32-bit Version
Install the tools.
2. Download a debug version of opencpn from
3. From windows, find and run windbg.
4. File->Open executable.... Select opencpn_debug.exe
5. Enter "g" (for "go") in the debugger command window.
6. Run opencpn as usual. Leave it running for a while, with full GPS
, etc. Stress test it. It may run a bit slower....
7. We hope the debugger breakpoint is hit. If it is, it means the heap got corrupted within the last second. There may be useful information in the debugger.
8. If the error line looks like this (we hope):
"HEAP[opencpn_debug-2009-10-21.exe]: HEAP: Free Heap block 12b88fc0 modified at 12b88fe8 after it was freed"
"HEAP[opencpn_debug.exe]: dedicated (0005) free list element 01DF4418 is marked busy"
then in the windbg command window, type
db 0x12b88fc0 l100
Note the address from the "HEAP..." line.
This will dump memory at the actual corrupted memory block. Hopefully we may recognize the data pattern being erroneously written, and give a clue to the opencpn module making the error.
With any luck we will stumble onto the bad memory write and nail this thing.
btw, are you running XP, XP Pro, or Vista?