FFXI Reboots My CompyFollow

This is getting really old, For the past 2 months my computer has been randomly rebooting on me, like it just restarts. I posted on the main FFXI forum a while back and was told that maybe it was my fan?? Anyway instead of getting a "real" computer fan i took my fan from my room and stuck it behind my computer^^;; anyway it helped a little (i guess) but more recently its been happening every 15mins on FFXI. please note i've only seen this happen DURING FFXI. Any ideas or want more info please post.