Firstly, this would go in either Beginner Sanctuary or Support. Secondly, make sure your game is up-to-date. I've encountered this problem before and reinstalling fixed it.
[18:04:54] <aracoon> Eureka is a powerhungry fag
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[13:13] <Eureka> also dota is kinda for pigfuckers
[13:13] <jalis> ban eureka
[13:13] <jalis> thanks