Any Solution For My Break Down Computer ?

Since my computer was still break down, i have to try many way to "rescue" my computer to "recover". I try to ask all my friend, and also explain to them about my case. All my friends was strange, why this will happend. They ask me when this matter begin? Then, i tell them, since i was format my computer from windows 7 to windows XP SP3. They all say maybe is the software crushing when i was formatting my computer. But, i tell them that i was try many many time format my computer already, but still the same problem. The problem occur when i was install any software inside. Who can help me ????? I want my computer to come back to me!