Problems loading winxp (office)

[bl4rg]

Occasionally, my computer fails to load up my OS. There is no pattern to this, and causes me to boot up in safemode; and causes me to use system restore to actually load up windows properly.
Anyone have any clues as to what causes this?

edit - forgot to mention SP2

 

[diduknowthat]

what step of boot does it stop at?

 

[bl4rg]

no idea, it just freezes up with the windows xp logo, and the colored bar moving across.