possible BSODs on winscp554

Hi, I upgraded to winscp554 from winscp512 yesterday (and used it a few times too, which isn't that usual) and had 3 BSODs since the reboot in about 24 hours (IRQ not less equal? not sure now since I needed to get back up in a hurry). It is possibly the first time I have enabled the drag and drop support dll.

The 'only' other change recently was a monitor brightness tool from Entech called mControl that uses DDC/CI to alter the monitors' internals (hardware stuff, but no drivers installed as far as I can see). Of course I suspected that most, but it was installed Monday, and I upgraded WinSCP Thursday (yesterday), and mControl wasn't loaded for at least the last crash. BSODs extremely rare these days.

Win XP. I was not actively using WinSCP at the time of the BSODs (although had been minutes beforehand in at least 2 cases, quite likely all 3). At least 2 were while using a Guest account over RDP (it freezes, I think "oh come on hurry up network", then go into the next room and see the BSOD).

My next step was going to be to disable drag and drop (DragExt.dll) but I have just uninstalled and downgraded as above. If you're extremely interested in replication I could do it again but I'm not too keen on BSODs, and it takes a few hours to crash.

I'm not overly worried about this but thought I should report it, just in case it helps solve a problem in general.

If it keeps happening after the downgrade/revert I'll post a followup to mark this as a false positive.

Thanks for your report. No one else has reported similar issue so far. If you are willing to try to replicate this, we appreciate it.

Well I feel (predictably) silly - it BSODd again today, downgraded version of WinSCP and no drag and drop dll. However I had recently been using it, again.

I have enabled minidumps (full memory dumps weren't completing and/or something installed itself over VS10 breaking the debugger so I can't see what caused the crash), however my suspicion has turned to something else: Took me a while to dig back to what I was doing at the time, it turns out minutes before the first BSOD, I changed my NIC TCP/IP DNS settings: primary to an external nameserver, secondary to my internal router proxy (rather than just the router as it has been for years). Migrating an old server so my local machine is seeing lots of DNS weirdness especially WinSCP as it was hitting multiple partly-resolved domains in a row, so maybe there's something the driver can't handle about that. This is a Gigabyte GA-P55-UD4P mobo with Realtek NIC, I know some versions of the driver have bluescreened on me before, but (I thought) the one I've been running for years was stable).

So quite possibly closer to the facts there, sounds more likely than a presumably non-kernel dll, I certainly wouldn't blame WinSCP as the cause.

A final update (hopefully).

The trigger (or really condition) for the BSODs does appear to be configuring my NIC's DNS servers (bottom of TCP/IP settings) one to an external WAN address (ISP's nameserver) and another to an internal LAN address (router's DNS proxy). Weird as that sounds.

The actual cause appears to be a driver called prio.sys from the "Prio – Process Priority Saver" utility I have had installed for many years, this adds a TCP/IP tab to the Task Manager which shows stats for all the current TCP and UDP connections (ports, bytes in out etc). I'm guessing there is some latent bug in its stats gathering code which couldn't handle WinSCP in particular triggering many DNS lookups with the settings mentioned above. I also had a BSOD starting Google Maps, so in the end it wasn't limited to WinSCP. Changing the DNS setting (the easiest solution for the moment) appears to have stopped the fairly regular BSODs.

The key is to have minidumps enabled (the Windows default?) and use a minidump viewer on that file to see what driver faulted. Otherwise it's just wild guessing and blaming the wrong software :)

Hopefully this followup will help someone out there, especially as WinSCP has taken the blame for the odd BSOD in the past I see.

Thanks for your feedback!