Problem Help Required

I`m new to this forum. I`m using Windows Vista & Fire Fox. I have just installed Bit Defender Total Security 2009. They problem i`m facing is.

1. Automatically my pc gets restarted in a day 5-6 times.

2. Even 5-6 times in a day Mozilla Fire fox crashes.

3. In scanning if any file found with Trojan/Virus Bit defender straight away deletes it. Even though in scanning options i have give first to disinfecte it & second quarintine it. But i thinks it doen`t works that way.

Before that i was using ESET there was no problem at all. Even i have reinstalled Mozilla fire fox but the same result. Pls advice at the earliest.