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In the same menu where you choose to go into Safe Mode you can choose to boot from Last Known Good Configuration (generally). Give this a try.<br />
<br />
When did it start happening? New applications installed?
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Did the last known...same thing. nothing new installed. 
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your system has been affected by virus there are two ways to clear it<br />
one way<br />
boot your computer in safe mode with command pompt <br />
type regedit in command prompt in registry goto <br />
search for mmc.exe where ever you find it delete that line<br />
once finished restart your pc<br />
and if you are not able open registry then you will have to go for second method<br />
<br />
second method<br />
reinstall your windows dont repair it will not solve the problem
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Uh no, not a virus...<br />
<br />
<a href="http://support.microsoft.com/kb/831885" rel="ugc nofollow">http://support.microsoft.com/kb/831885</a><br />
<br />
Hotfix courtesy of microsoft
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Could you let us know what you have tried? It will help rule things out and will help cut down on getting possible solutions youve already tried.<br />
If you post back the system specs (manufacturer, model, processor, chipset, etc.) it may shed some light if its one known to be prone to a certain type of problem eg. dell gx270's bad motherboard rep.<br />
<br />
Going on what you have posted, my first instinct would be to check the memory. &nbsp;If you have more than one stick, try removing all but one and try rebooting, if it still gives you problems, try the next, and so on, if it works with a particular module removed you will know you have a bad stick of memory.<br />
<br />
You will also want to try resetting your bios, this will be done by either a jumper or removing the battery on the motherboard... once we know what motherboard you have, I can provide you with more detailed info on how to do this for your particular system.<br />
<br />
While you have the cover open to reset the bios you may want to check for leaking or bulging capacitors on the motherboard, if your not sure what a bad capacitor looks like, &nbsp;just do a google image search for faulty capacitors.<br />
<br />
Next I would pull the hard drive out and put into an external hard drive enclosure (or if no enclosure available, set it as slave into a working pc), back up all important data, and then run diagnostics on the hard drive. &nbsp;I personally like hdtune &nbsp;<a href="http://www.hdtune.com/" rel="ugc">http://www.hdtune.com/</a> &nbsp; <br />
<br />
If problems still persist, try removing all unneeded hardware (network cards, video card if possible, cd/dvd drives, etc...), then try booting again, if things boot fine, reinstall the other parts one by one until you find the one thats causing the problem. &nbsp;Dont be alarmed if your problem goes away altogether, many times (not often, but it happens) simply reseating a part is all thats needed.<br />
<br />
And you still have a problem, at least it will now be narrowed down to the very basics.... either power supply, motherboard, processor, or possibly just a repair/reinstall of the os.<br />
<br />
When you get down to these , I would start off with the swapping out the power supply with a known good one first if possible. &nbsp;<br />
If that is not an option, then I would say move on to a repair install of windows. &nbsp;If that fails, chances are your looking at a bad cpu or motherboard, and unless you have another compatible cpu or motherboard to swap around, there really wont be any way to know for sure which one the real culprit is.<br />
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Before you start tearing stuff apart, and if you have the XP CD, you may want to give the repair option a try.<br />
<br />
Here ( <a href="http://www.webtree.ca/windowsxp/repair_xp.htm#How%20to%20Repair%20Windows%20XP%20by%20Installing%20Over%20top%20of%20Existing%20Setup" rel="ugc">http://www.webtree.ca/windowsxp/repair_xp.htm#How%20to%20Repair%20Windows%20XP%20by%20Installing%20Over%20top%20of%20Existing%20Setup</a>: ) is a tutorial.<br />
<br />
It very well could be a virus, it could be a hardware issue, but start with the least painful thing first... this is pretty painless.<br />
<br />
If you have ultra important data you should probably pull the hard drive out before you do anything, hook it up to a second system and back it up. You most likely won't lose anything, but you never know.
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While a repair install is less painless at first glance, if the hard drive turns out to be failing, you risk doing more damage and having less chance of recovery.<br />
That is why I suggest the non-destructive testing be done first, and then backing things up before doing anything that writes to the drive.
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Thank you so much. You saved a lot of time that would have required backup, installation etc. etc. :)
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<div class="content wysiwyg-content">
Windows XP home edition is not letting me login. And gives this error on start up:<br />
mmc.exe - Application Error The instruction at &quot;0x0040bd3d&quot; referenced memory at &quot;0x003ff2d0&quot;. The memory could not be &quot;read&quot;<br />
Click on OK to terminate the program<br />
Click on cancel to debug the program<br />
<br />
Same error in safe mode too. Tried a lot of things, didnt work. Please help.
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Windows XP home edition is not letting me login. And gives this error on start up:
mmc.exe - Application Error The instruction at "0x0040bd3d" referenced memory at "0x003ff2d0". The memory could not be "read"
Click on OK to terminate the program
Click on cancel to debug the program

Same error in safe mode too. Tried a lot of things, didnt work. Please help.

Cannot login windows xp. cannot find solution. please help

Microsoft Windows XP is the sixth release of the NT series of operating systems, and was the first to be marketed in a variety of editions: XP Home and XP Professional, designed for business and power users. The advanced features in XP Professional are generally disabled in Home Edition, but are there and can be activated. There were two 64-bit editions, an embedded edition and a tablet edition.