Hi,Seems my confidence was misplaced as it happened again to me yesterday evening - twice :( On each occasion I was doing no more than composing emails.Same STOP Error IRQL_NOT_LESS_OR_EQUAL (0xA)Back to the drawing board.I'm thinking I'll leave my PC on overnight running in SAFE mode and see whether it crashes.Mike

Did you pull the SB sound card and test? My guy I mentioned above got impatient after 4 days and bought a Montego, so testing his system without the SB card was inconclusive. I installed the Montego for him (after a format) but haven't heard from him since.

Hi Greg,No, I haven't gone down that road as yet (removal of sound card), but it's there on my list of things to try along with Verifier (I'll need to bone up on that one) and reseating/swapping my ram modules. I left my rig idling overnight in SAFE MODE and 7 hours later it was fine. I could be wrong, but I was hoping that this might eliminate hardware and possibly the PSU as the cause (since this can happen at idle). I then thought I would turn my attention to the drivers, starting with the graphics drivers as this was mentioned in one of the minidumps.While in SAFE MODE (at the end of the 7 hour period) I thought I would try firing up Everest Ultimate Edition and run the stress test. Much to my surprise it ran and I started the test. It was only going for a few seconds when I realised I hadn't configured it to display the parameters I wanted to see so I stopped it. Within seconds of having done so...you guessed...another STOP error, but this one was different:PFN_LIST_CORRUPTSTOP: 0x0...4E (0x0...99, 0x0..19A02, 0x0...0, 0x0...0)The odd thing about all this, and it could be significant, is that my system seemed stable for a good 10 days after returning from a fortnight's holiday. No crashes even when left on for several hours and under all sorts of demanding circumstances. I was just starting to feel that the problem had resolved itself somehow when perhaps the inevitable happened! Ugh!It's got to the stage when I am having to save stuff like this response periodically as I type in case I have to start over.The ATT advanced tweaks turned out to be red herrings as I mentioned before.You did say you installed the Montego (after a format). Unfortunately, I'm sure you would agree, that the format denied you of having any possibility of narrowing down the cause - hardware, drivers or whatever. Perhaps the guy's system would have been okay reusing the original card. We'll never know.Edit: I thought I should mention that these most recent BSODs have not resulted in the creation of a minidump file. I see the message at the bottom of the screen where it implies the dump file is being created but nothing follws to tell me that it has completed.Regards,Mike

Hi,In a previous update I stated wrt ATT:"I had enabled MT Support some time ago and had set the Maximum number of working threads to 2 (as per Koroush Ghazi's recommendations)."I stated also that I had flirted for a time with a setting of 4 working threads and had tried backing off again to 2 since I was suspecting this might have been the source of the instability producing what appeared, from one minidump, to be graphic driver related crashes/stop errors. Unfortunately, these intermittent crashes continued and for a time I was thrown off track.I am now happy, and relieved, to report that the problem seems to have been resolved:I returned once again to that Multi Thread Support tweak which, to be fair, Ray Adams had marked with three exclamation marks as being 'Experimental'. I disabled the tweak and, would you believe it, absolute stability has returned once again!All of which only serves to demonstrate that in many cases system problems are frequently caused by the user's irrepressible desire to fiddle with settings about which he has very little understanding - yes, I admit it, mae culpa :-(Mike

Sounds promising, Mike. Don't for a minute think you're the only one here who has experienced......system problems are frequently caused by the user's irrepressible desire to fiddle with settings...LOL, yeah like nobody else here doesn't know what that's like. :-) Cheers,

Hi again,For those that have been following this thread I thought you might be interested to hear that this matter has finally been resolved. Yes I did say, and with some confidence, RESOLVED!It now looks like my previous theories may just have been symptom manifestations of the underlying problem: faulty memory, or more specifically a faulty memory address on one of my Crucial Ballistix DDR2 PC2-6400 modules.After my last post I was hit again several times with the BSOD STOP: 0A. So I decided to run a further extended test on my memory modules with Memtest86+ and this time it was reporting numerous failures while running test #4 (moving inversions) and always at the same memory address. I run the 2x1G sticks in dual channel mode.My findings were discussed with Crucial and the old modules RMA'd.The replacement modules were duly installed and were immediately recognised correctly by the System BIOS (unlike the old modules where it had to be done manually. This time I left all the memory timings on Auto as recommended by Crucial.Now my system boots more quickly and XP loads fully everytime without any hangups. I have encountered NO errors now for 2 weeks and general performance and stability appears to be very good and remains consistently so.I confess my confidence did take a bit of a knock while I have been wrestling with this problem, but gradually it has now returned. In fact, I have even gone as far as update XP with SP3 and my graphics drivers from the 7.10 Catalyst (WHQL) to the 8.10 (WHQL) driver set and everything still works! Well, nearly everything, as I have since encountered an issue whereby my custom monitor colour calibration does not stick while running in 3D Full Screen. CCC does not help nor does ATT seem to correct the problem. But that's another story :(As time wore on I really did reach a stage when I believed that I was faced with a major hardware issue, possibly the mainboard/AM2 daughter board, but thankfully this has proved not to have been the case. With some trepidation on my part the system has been thoroughly tested for stability (twice) with Hot CPU Tester Pro 4. This utility tests CPU, chipset and virtually all parts of the mainboard for errors/bugs, defective parts and components. I gather it is used in many labs and governmental organizations around the world as a reliable stability testing utility. Anyway, it certainly cheered me up.Here's a copy of the results following the second 6 hour run:Hot CPU Tester Pro 4.4.1Copyright

Glad you got it solved MikeAs I said at the beginning of the thread... IRQ LESS THAN is usually either memory crash releated or driver crash related, one of the two

Hi Nick,Yes, glad and VERY relieved! The prospect of potentially being faced with weeks of software reinstallation and configuration, had this been a mobo problem, did not appeal at all. I'd much rather defer all that for a while yet.I watched the Hot CPU Tester Pro 4 while it was doing it's stuff and was amazed (and anxious, it has to be said) to see the way it juggled the various testing modules - frequently several appeared to be running concurrently. When I saw the results I couldn't help thinking not bad for a so-called 'budget board' that's been in constant use for over 2 years and the AM2 daughter board for 7 months! Not bad at all! Also I monitored (logged) the core temps of the CPU throughout using Core temp 0.99.3 and they peaked at 57