XP service pack 2 problems

[mojo]

a couple days ago i dled and installeed xp service pack 2 and when it was finally done i would load up the computer and as soon as it came to my desktop the computer would automatically restart. since everything on my computer was useless i decided to just use the system recovery thing to fix it. i still want to get SP2 because i need it for visual c++. does anyone no how to fix this problem so i can get SP2 working.
-mojo