error message

I'm getting this error message every time I log on,can anybody advise me how to stop it? I have windows 7.

script error
line; O
char; O
Error; Script error
code; O
URL; http//colo.cachefly.net/js/min.inject.js?
id=PjsoPyE&ad_label=CouponDownloader&ad_label_link=http:
//www.coupondownloader.com/aboutthisad.php

Do you want to continue running scripts on this page

Then there is a choice of YES or NO
ive been clicking yes as I don't know what else to do.
thank you