Sometimes if the files were rar'd up with a newer version of winrar and one tries to open the rar file with an older version of winrar you can get this same error message. Might want to check out a newer version of winrar. I have experienced this myself. Not necessarily the problem but might be worth checking out.

There are 10 kinds of people: Those who know binary, and those who don't. 

A whiner is about as useful as a one-legged man at an arse kicking contest.