My computer wont boot up

[jana978]

I have a Dell Inspiron 530 running Windows Vista with Trend Micro antivirus software.  I suspect a virus because when I turn on my computer it wont boot up.  It is stuck on the main start up screen and F2 and F12 will not work as is the keyboard (USB) is not working.  My mouse isnt lighting up.  I have checked all connections. 
Thanks in advance for any help.

[Allan]

Based on the information you've provided a virus is the last thing I'd suspect. What happened the last time the system worked properly (new hw, sw, error, etc)? And please define "the main startup screen".

[jana978]

A few days ago it was acting up on start up and shutting down.  As far as I know there hasnt been anything new put on there.  I have teens thats use the computer so there is really no telling.  The only screen that comes up when I turn on the computer says "Dell bios 1.0 something or another and it its when you have the option to press F2 or F12 for set up or boot menu.  I cant select those options as the keyboard  hasnt started up and wont start.  It just gets stuck and all I can do is manually shut it down by holding the power button down.