computer melt down!

I am REALLY annoyed at my computer.
 this morning and a lot of other mornings before my computer has been shutting down after someone has been on. but its only been like ten min. for them to start playing or writing or blogging or whatever when....... BOOM! the computer just shuts down on you!!!!!
 i call this COMPUTER MELT DOWN! (hense the tittle)
HELP!!!!!
  i cant figure it out! is the computer overworked? did my dad do this on purpose? but the only time it actually does it is when its on the kids server!!!!

AAAAAAAAAAAAAAAAAAAGGGGGGGGGGGGGGGGGGGGGGGGGGG!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 i'm so confused! i thinks its because my BROTHER is constanly on it!!! when he isnt doing school (that means when my mom isnt standing over him telling him what to do and HOW to do it) hes on the computer!!! I think hes usualy on there for like SIX HOURS!!!!!!!!!
 anyway can SOMEONE tell me what to do!!!! i'm so frustrated i can barly THINK!!!!!!!!!!!
thanks for reading anyway. see you next time.

   -becca!