I recently posted a thread in the malware section of the forums regarding my problems. However, after extensive scanning, it seems that the problem is not due to malware.
Here's the first post in the thread describing the problems.
Here's my computer stats:
Intel® Core™2 CPU 6300 @ 1.86GHz
Nvidia GeForce 7900 GS
Creative Sound Blaster Audigy
Okay, so it started about a month ago. First, my sound card stopped working. Usually, a restart causes it to work again. Then, occassionally I'd get this windows security message in my taskbar about not having any anti-virus running, even though my AVG free was running. I assumed it was just windows not recognising it sometimes, because the security message doesn't appear all the time. After about a week or two, the security message became permanently there. Again, i just ignored it, because my AVG was running perfectly fine. However, a few days later, while browsing the web, the computer just died. Screen went blank, and the power button blinking orange. Restarting the power and everything didn't work, it refused to start. Since it was still under warranty, i called up Dell and they sent someone done. He replaced the motherboard, and it could work again.
Just a few days after that, the same thing happened, just died out of nowhere. So, i called up Dell again. This time round, when they sent someone down, I wasn't able to be there, but from what i can see from the details of work from the receipt, he replaced the power supply, flushed and upgraded the BIOS. (From 2.3.0 to 2.4.0). When i came back and checked the computer, i realised my sound wasn't working anymore. Device Manager didn't even detect the sound card. Since the sound card is already around 4 years plus old, I thought it had spoilt, so I just removed it and used the onboard sound. (I tried plugging the sound card into the other PCI slot, didn't work either. And my sound card is my own, and therefore not covered under the warranty.) Less than a week later, the front port which i use to plug my speakers in to the onboard sound, stopped working. Only the one on the back worked. It was around this time that the permanent security error of not detecting any anti-virus came back again.
I called up Dell again (I bet they were really fed up with me by now. Haha) and they sent someone down again. On the evening that he came, when he started up the computer, AVG didn't even load at all. Tried running AVG directly from it's folder didn't work either, it just refused to run. Also, it was at this point the technician realised that he couldn't download anything using IE. The downloading screen will come up, but when the download finishes, the file will not be anywhere to be found. I'm not sure when this started, because I use google chrome. Also, he tried replacing the front USB hub, but the front sound jack still didn't work. At this point, he recommends a reformat and states that he cannot help anymore because it's more than likely a virus or software problem. (That isn't covered under the warranty either.)
So, I bought an external hard drive, and backed up only my essential things and reformatted. I scanned the external hard drive with AVG before i transfered the things back, and it was clean. For some weird reason, my sound card didn't work right after my reformat. It was only after a few days later, when i decided to put the cover back on onto the CPU that it worked.(I have no idea why i even left the sound card plugged in when i put back the casing cover...) It's been less than two weeks since the reformat and now the problems are coming back again. I saw the security message about no anti-virus, even though AVG is running. A restart later, the error was gone. Then for the past few days, my sound card has around a 50% chance of working. Sometimes a restart makes it work again, sometimes not. More often than not, it starts out working, then after a few hours or even a few minutes, it just stops working. No errors anywhere or anything, just no sound at all. (This refers to both the sound card and onboard sound)
Earlier today, i downloaded Avira Anti-vir personal. A full scan doesn't show anything at all. I've been scanning with AVG free and Spybot every few days since the reformat. AVG free hasn't detected anything so far. Spybot just catches the usual spyware and removes them without any trouble.
Here's the link to the thread in the malware forums if anyone happens to need it. http://www.bleepingcomputer.com/forums/top...ml#entry1343334
Also, just today, my sound card wasn't detected when i turned on the computer. I had to scan for plug and play devices on device manager for it to appear.