Dell Optiplex Gx 240 XP SP 3

Hey Guys!! 

 New to this forum, hope im in accordance to ettiquete.  As the Subject says i have a older model  Dell Optiplex Gx 240 running windows  XP SP 3. 

I recently had to remove several worms and malware from the HD. from the begginig i could not load my virus scanner from the boot menu. i changed the order of the boot sequence to CD ROM 1st. the keyboard functions during bios but when the virus scan asked for my pressing of a key to boot from CD. i would not resond. i eventried the recovery disc, same isseu would not allow me to boot from the disc due to not being able to engage the keyborad when promptede. the keyboard is great. it works once i get past the welcome screen but would not allow me to load during boot. so i downloaded security essentials from microsoft. was able to remove the viruses that way. But heres( where i am now) I ran msconfig  to set the system to boot into safe mode. and since then i cannot use the mouse or keyboard at the welcome screen. so needless to say everytime i restart the computer i cannot get past this screen.  SOME oNe Please Help!!!

Thanks in advance Guys