Autocorrect Problem

Hello,
I've been using iPhones since day one and have never seen this problem. Last week I bought my girlfriend an iPhone 4. She is in absolute love with it! She is coming from an LG EnV 2.

The problem is when she that whenever she types "so", the iPhone will autocorrect it to "So^" (both without quotations).

At first, to fix this, I kept writing "so" and hitting the "x" on the autocorrect box. After about 10 times in a row of doing this, I figured this wasn't going to work.
Then I went into settings and reset the keyboard dictionary. This worked for about a day but then the problem came back. I reset the dictionary again and she just texted me saying it was happening again.

Anyone have any idea what is causing this? I heard that if you have a weird word in your contacts sometimes your phone will autocorrect to that word, but this is not the case.

Thanks!

 

I hate to bump but this keeps happening and it is really frustrating.