SSRS - Report Parameter Format issue

I have a bizarre issue with uploading a report made in VS 2005 uploaded to CRM 4.

the date formats show up correctly when running the report in VS and when uploaded to our report manager. However, when I upload it to CRM, both dates show up in different formats (see above image). Even stranger is that even though it shows "05/Jan/13", the report interprets it as May 1st.

I cannot find a difference in the setup of these parameters:

    <ReportParameter Name="beginDate">      <DataType>DateTime</DataType>      <DefaultValue>        <Values>          <Value>=DateAdd("D", -1.0 * DatePart("D", Today) + 1, Today)</Value>        </Values>      </DefaultValue>      <Prompt>Start</Prompt>    </ReportParameter>    <ReportParameter Name="endDate">      <DataType>DateTime</DataType>      <DefaultValue>        <Values>          <Value>=Dateadd("D",-1,DateAdd("M", 1, DateAdd("D", -1.0 * DatePart("D", Today) + 1, Today)))</Value>        </Values>      </DefaultValue>      <Prompt>End</Prompt>    </ReportParameter>

Why would it show up correctly one way and produce quite different results the other?