50mm 1.8 front focus problems

Well, I bought my second 50 1.8 last night hoping to get a better copy than my last one. This one is also consistantly front focusing which is very disappointing. I love the images this lens produces, even wide open at 1.8, but if I am unable to get what I want in focus it doesn't do much good to keep it.

My question is, should I take it back to try a 3rd or should I give up with this lens? I am using this on the digital rebel, others have suggested that it may be the camera front focusing. To anyone that has sent their camera in to canon, did it come back focusing correctly and how long did it take?

Thanks
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Todd Putman
http://www.dataserv.net/~toddp/gallery