"When I turn on my computer @ home it trys to start then it goes to a black screen and it says i can start it safe mode... and 2 other safe modes, regular mode and the last one that worked... i tryed all of them... do i have a virus?? does anyone know how to fix it?"
Click on START> click on CONTROL PANEL> click on SYSTEM> click on the ADVANCED tab> click the SETTINGS button for STARTUP AND RECOVERY.
Make sure ["Microsoft Windows XP"/fastdetect] is your default operating system then uncheck the boxes for "Time to display list of operating systems" and "Time to display recovery option when needed"
click OK then restart your machine...it doesnt sound like you have a virus
here is a pic of what your screen should look like
http://s31.yousendit.com/d.aspx?id=1LQQNUC7RLEF21PR0QHUOWW04X