Decent Computer, bad output

It seems as though I have 2 problems. The first being that the computer doesn't always start, sometimes it stays at the black screen right before the windows loading screen and I have to restart it, sometimes more then once.
The other problem that I have is the real issue at this point in time, my computer is not maintaining a steady CPU usage and when it jumps is causes my games to lag, severely. I don't actually know what I'm talking about but this is what I have boiled it down to.
So I used a program called Process Hacker to see what was going on, I noticed that every time the usage (usually hangs out around 2%-4%) jumps up to 13%-28% Lsass.exe goes with it. So, I open up Lsass.exe in Program Hacker for a closer inspection and it turns out that sure enough, this is the program causing the sudden increase. So I close it. That was a bad idea, so I research what it is, turns out that it isn't bad, but in my case it isn't exactly good. I made sure the services were the right ones and what not.
This was not a problem a day ago, however I had to restart my computer and my games were running terribly. So I restarted my computer again, and then again, and the problem went away. Then I was cleaning the other day so I shut my computer down and I haven't been able to get it back up running at par since.

my computer:
AMD Phenom II x4 920 ~2.8ghz
Radeon Sapphire HD5670
Windows XP sp3

 

What OS? What security software? What model? Did this happen all at once? Almost sound like a combination of hardware and software/malware problem. So it does run now, just poorly?
Could be a bad memory board. Try running memtest, download from HERE
Also, open the side panel, assuming not a lappy, and make sure all connections are good and tightly seated.:wave:wave:wave

 

Thanks for the assistance so far.

The OS is Windows XP, SP 3. The security software that I'm using is avast!

I will go over a brief history of my computer so you have an idea of where I stand. - I got the computer in January, right off the get go I noticed that it only got through the startup 75% of the time, other times it would hang on a black screen. Then, after a while of gaming and what not the computer started to restart itself frequently, and then it would only start up when it felt like it. Sometimes it would just not start up at all. So obviously, I took it back to the place I got it and told them to fix it. They said that the problem was that the motherboard and video card had been awkward models to put together and they actually fused together, melting each other and what not. So he got me a new mobo and video card. The motherboard wasn't compatible with my processor but he didn't find this out until after he tried to shove it in, so he bent a couple pins. Then he got me another new Motherboard, somehow managed to straighten the pins on the processor and everything was good from there. Take the computer back and notice that the start up issue still persists but other than that everything is fine.
So, you mention that it might be a hardware problem and it makes my head hurt, because I have pretty much replaced/upgraded everything on this computer once already and it's not even 4.5 months old yet.

I ran memtest and the memory is good, or appears to be at least. I pulled the ethernet cable out, to see if it was network traffic causing the disruption but cpu usage still goes through little spikes. I managed to close lsass.exe and then just abort the auto-shutdown that it induced but it seemed like it was only a temporary fix to the problem.

Thanks for your reply, hopefully I can manage to isolate the problem eventually, but for now everything seems to be "working fine" according to the computer. The thing is, when computers are involved there is no such thing as "working fine" I've come to realize.

 

Given that this was a second hand machine, it is also very possible that other antiviruses have been used on it. I routinely run both the Norton and Mcaffee removal tools just as a precaution, they don't fully remove with Windows. And the remnants cause erratci behavior. You can find them on the bottom of this page HERE

I'd also open a command prompt and type chkdsk /f
Note the space before the /
Then reboot and let the test run. :wave:wave

When it does start, does it run better in safe mode maybe?

Still not certain if this is hardware or software or both.confused

 

The machine wasn't actually second hand, it was built for me. Everything about it was brand new though. I'll try running chkdsk.

Not knowing if it is hardware or software makes this problem seem so inconceivable.

 

Did you pay this person to build it for you? Because it is almost brand new and they should be taking care of this.

Not booting up is normally hardware related. Running erratically or poorly is normally software/malware related, but not always. Could be overheating. I can't see how a video card can melt into the MOBO, that sounds like a LOT of heat!

I'm no expert with this program, but see if this can give you some insight as to what is going on;

http://majorgeeks.com/SpeedFan_d337.html

And maybe somebody else here knows more about this. :confused

 

They had built it for someone who decided they would just buy one from Best Buy instead so he sold it to me.

He should be taking care of this yes, if the problem is with the hardware.

Plus, I have come to the conclusion that he isn't that great with computers, seeing as how every time I've given my machine to fix it he comes back telling me absurd tale about something.

There has been a breakthrough though and it came by using the program you recommended for me to use, Speed fan, because I noticed that the Temps 2, and 3 had little fires next to them while the problem persisted. So, then I did the chkdsk or whatever and rebooted. The problem seemed to have dissipated a little bit...I ran Speed fan and noticed that the little fires had turned into little blue arrows and the computer ran nicely. Therefore, at this point in time I have been able to determine that my computer overheats when it runs after the boot sometimes, but sometimes it does not. It can run forever without overheating as long as it decides not too while booting. It's hit or miss right now. But, at least hit is a possibility, that's a win in my books.

 

Glad to hear that it is running better but, unfortunately, I doubt if the chkdsk is responsible for that.

It sounds like the fans aren't kicking in when they should. Can you enter the BIOS and check all of the settings to see if you have some options for fan control. Some BIOS systems will give you more control.

I also have to question if he did a proper job with the heat sink installation. :wave:wave

 

I'm not sure if he did or not...I really don't have the technical know-how to figure something like that out. I'll go into the BIOS and see if I can find anything but for the most part the BIOS just confuses me and I eventually leave it be. Thanks for everything by the way, it's been really nice to actually get responses in good time and very helpful.