Windows 7: CPU and Memory running very high - please help!

A few days ago, I get this little Windows pop-up on my taskbar saying that my computer is unprotected and has been infected with a trojan (couldn't remember if it said which one exactly but I believe it said Alureon?). Afterward, my computer has been running very slow and the CPU/Memory widget I have pinned on my desktop shows they are pretty much maxed out, all the time, even while not having Internet Explorer or programs open (none that I have knowingly opened myself, anyway). I went out and bought McAfee Anti-Virus 2013 yesterday hoping this would resolve the problem. It did find 10 trojans and removed/quarantined them, but nothing has changed as far as system performance goes; everything still runs slowly, and opening even the smallest of programs like a calculator takes at least a few seconds.

I apologize if this thread is in the wrong forum and if I can be more descript, but I am more than willing to answer any questions or take screenshots if needed. Thanks so much for anyone's help concerning this matter!

P.S. - My computer isn't a beast by any means (Toshiba Satellite C655 running Windows 7 Home Premium 64-bit, 2 GBs RAM, Intel Celeron 2.2 GHz - was an Xmas gift), so I don't expect some sort of vast improvement but it used to run MUCH smoother and quicker and I don't want to see it die on me!

Welcome GHP222,


Try downloading & running the FREE version of MalWareBytes to check your computer for spyware that might be slowing it down.

Malwarebytes : Free anti-malware download

Alureon.
Alureon - Wikipedia, the free encyclopedia
It has been around for 5 or 6 years but still nasty.
Using another clean computer I recommend changing all passwords.
After doing as Doc Brown has suggested I would also do these in order.
Windows Defender Offline
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Anti-rootkit utility TDSSKiller
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Information.
How to remove a bootkit
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Rootkit and Bootkit infections can be very nasty infection and they can also allow other infections into your computer.
Please let us know what other infections are found because it will help us help you.

Thanks so much guys. I think the MalWareBytes download may have done the trick, as I have just restarted my computer after a full scan to see that my CPU and RAM gauges are much lower as well as noticing what seems to be a much faster system overall.

Reading about Alureon, is there anything I need to do aside from changing passwords on certain websites that have some of my confidential information?

Oh, and Layback - I also ran the Kaspersky root/bootkit tool and it found and removed something so it looks like it's smooth sailing!

I wouldn't be so sure quite yet. You used Malwarebytes and it found things it's designed to find. You used Kaspersky and more things that it is designed to find were found. That is why I listed different programs to use. No program finds them all. I would still use Windows Defender Off Line and this also.
Free Online Virus Scanner | ESET
If their is any of these infection left behind they will just steel your new passwords and leave the back door open so their friends can find their way back to your computer. Those types of infections are very clever.