Unexpected reboot - no BSOD?

[watercooled]

I've just gone to open a minimised pdf document (a fairly large one if it matters - around 30MB) it opened OK but I scrolled down a bit and the screen went black and the system rebooted showing me the boot selection menu at the next boot. The was no BSOD or anything and I can't find anything in Event Viewer about the event except for "The previous system shutdown at 22:14:15 on ‎20/‎11/‎2009 was unexpected." and "The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly." also no dumps were created. What could have caused this?

[Dingo]

System specs would be useful as would knowing what other applications you had running at the time.

Possibly lack of memory could cause unexpected shutdowns, but equally, could lack of power or overheating.

[CyberChris]

I will go with hardware related, I would check by stressing the system to see if it happens again.

[watercooled]

Was having BSODs on the RC maybe once a month or less - a CPU cache error but never did find out what was causing it - most likely a bug in OS because it's never happened in the full version. Stressing the system doesn't help to recreate it. Specs are AMD 5050e CPU, 780V motherboard, 4GB DDR2 RAM, and a Scythe Shuriken cooler and a 350w Antec PSU supplied with the Minuet case (made by Seasonic). CPU is plenty cool enough and I've checked PSU output voltages with a multimeter because of software readings displaying out-of-spec voltages (tested OK). Applications include Firefox, SumatraPDF and of course background tasks including Security Essentials and CCC. Done a virus scan with SE and ESET online scanner and neither found anything.
Thanks for helping.

Edit: Sorry forgot to mention OS is 7 HP.

[Mblaster]

My first guesses for something like that would be power loss or over heating. It doesn't sound like you were doing anything CPU intensive, so it's probably not overheating, so I'd give the power connections a check to make sure they're not loose and check there's no power switches down by your feet that you might accidentally kick (this has happened to me far too many times!)

If it's not a recurring thing then I wouldn't worry about it.

[watercooled]

Yeah it's happened before because of power fluctuations but I didn't see any lights flickering and as I said I have a Shuriken cooler and temps are fine, besides if that was the case I should have seen an overheat warning on reboot. Like you said though it's not worth worrying about since it's only happened once.
Thanks.

[o0~Wiz~0o]

Hard resets on the Dell systems in the link below were cured by a video driver update. Maybe worth a shot if yours are not current.

http://forums.adobe.com/thread/394887

[watercooled]

Strange! I'm currently running 9.9 CCC and have the 9.11 installer on my desktop waiting to go but I keep putting it off because upgrading video drivers messes up the icons on my desktop yeah sounds daft but I have a lot and I keep icons in groups so I can find them. I keep meaning to install some software for that but I can't remember the name of the one recommended to me (anyone know what it might have been).

Edit: might have been ObjectDock...

[o0~Wiz~0o]

I assume adobe is fully up-to date?

[watercooled]

Not using that bloated monstrosity, I use Sumatra which is up to date yeah. Oh and I found that software again - http://forums.hexus.net/1787916-post6.html

[o0~Wiz~0o]

Maybe it would be worth trying the monstrosity to see if the problem persists?

[watercooled]

It's never happened before so don't have any reason to believe it was Sumatra and I'd really rather not use Adobe - I don't see the point in several hundred MB for a piece of software that reads PDFs, is slow to load even on very fast systems and needs updates practically weekly because of all of the security exploits constantly being found in it and I could go on for ages about why I don't like bloat but I won't SumatraPDF weighs in at around 1MB and does everything I need as well as being so much quicker at everything and the install consists of ONE file plus an uninstaller and a prefs file and some reg entries for file association etc which are optional.

[o0~Wiz~0o]

Sounds quite nifty. I have taken note for future use. So far on win7 I have not needed a pdf reader as google has let me preview the odd few I have needed to see.

[watercooled]

Would definitely recommend it - you'd be surprised how much faster it is!!