Ive had everything replaced except the CPU and Motherboard, so its one of the two
I have tried new ram, harddrive, CD Burner (Yeah, I just wanted to make sure), PSU, Video Card, and just about everything else.
My temps never go over 38C so I know it can't be over heating. For the past year I have had to reinstall about 6 times. And I RARELY download and use a good antivirus. The biggest thing I have on here is my music and Photoshop.
I am the go-to guy if my friends need help and it's usually just ram, HDD, and all like you said but I have tried everything.
It's an HP Pavilion a250n given to me by my mom, it wouldn't turn on for her so she gave it to me, I threw in a new PSU and all was good for about 6 or so months then I started having the random crashes, freezing, and it will beep once in a while. I am guessing it was struck by lightning and effected the mobo in some way.
And no it's not overclocked, as you probably know HP doesn't allow it, at least as far as I know.
If I went ATX what would be a good case <$80 that has a side window and at least 4 fan mounts. I have about 10 fans here from previous PC's.