I have never set a BIOS password on my main computer. I have, in fact, never set a BIOS password on ANY of my machines( trusting and lazy, I guess). I came home from work tonight to find my main pc acting weird. I attempted to open the web browser and got nothing; it was as if I hadn't clicked on it at all. Task manager displayed but simply sat there. I attempted to reboot the pc, but it was completely unresponsive. I ended up pressing the power button to turn it off, and when I turned it back on, I was greeted with a screen asking me for the system password. I could not get into BIOS or boot from CD without the new password it was asking for. The pc is running Windows XP Pro SP2 and is a member of a domain (Server is 2003 SP2). Server, pc in question, and the one other machine (Windows 2000 Pro) were running McAfee AV; the AV has been uninstalled on the server and the W2k box (not by me), and the W2K machine has no internet. They are both shut down and the router is unplugged since I found this. I have a suspicion it's a rootkit infection. I have removed the CMOS battery from the XP machine because I've read that removing the battery for a certain number of hours can sometimes reset the BIOS password, but I'm concerned that if it IS a BIOS rootkit, a simple re-install of the OS won't solve the problem on any of my machines. Has anyone else experienced anything like this? If so, any advice and/or experience that can be shared would be greatly appreciated. Thanks!