can rooting mess up my ability to send/receive mms messages?

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http://androidforums.com – Okayim on Alltel and I've rooted my phone, well today I noticed I can neither send or receive moms messages, but I can receive SMS and can browse the web over 3g but when sending an moms it hangs and never sends, could rooting cause this? And if so how do I fix it? Is there a market app where I can alter my APN settings? As my alltel phone has the APN settings hidden I believe. (General)