Yahoo. I have been having problems with yahoo, i belong to a yahoo group and every once in awhile

Question

I have been having problems with yahoo, i belong to a yahoo group and every once in awhile i will get messages that are garbled even when i reply to someone. And it only happens with yahoo. I have done a virus check and nothing, also changed my outlook addy just in case and still a problem. I have no problem with google groups. I reinstalled explorer just to make sure and that did not work. I have been trying for 2 weeks to figure out why and cant seem to find it. I put on gmail to see what happens and never got one at all,but took it off as i did not like it, and boom, the garbled messages came back.They also never came in my outlook either. Hope you can help me I am at my wits end trying to figure why yahoo is doing this. Here is what it looks like thanks
Here is some of it anyways
--------------Boundary-00=_09UXWCW0000000000000
Content-Type: multipart/alternative;
boundary="------------Boundary-00=_19UXRN00000000000000"

--------------Boundary-00=_19UXRN00000000000000
Content-Type: Text/Plain;
charset="utf-8"
Content-Transfer-Encoding: quoted-printable
|**|begin egp html banner|**| -->

<img src="http://geo.yahoo.com/serv?s=97476590/grpId=16531829/grpspId=1705083764/msgId=319961/stime=1224339332" width="1" height="1"> <br>

<!-- |**|end egp html banner|**| -->

<!-- |**|begin egp html banner|**| -->

<br>
<div style="font-family: verdana; font-size: 77%; border-top: 1px solid #666; padding: 5px 0;" >
Your email settings: Individual Email|Traditional <br>
<a href="http://groups.yahoo.com/group/LotsofChatandFun/join;_ylc=X3oDMTJnZXVqc3I0BF9TAzk3NDc2NTkwBGdycElkAzE2NTMxODI5BGdycHNwSWQDMTcwNTA4Mzc2NARzZWMDZnRyBHNsawNzdG5ncwRzdGltZQMxMjI0MzM5MzMy">Change settings via the Web</a> (Yahoo! ID required) <br>
Change settings via email: <a href="mailto:[e-mail]?subject=Email Delivery: Digest">Switch delivery to Daily Digest</a> | <a href = "mailto:[e-mail]?subject=Change Delivery Format: Fully Featured">Switch to Fully Featured</a> <br>
<a href="http://groups.yahoo.com/group/LotsofChatandFun;_ylc=X3oDMTJlcm50bTBnBF9TAzk3NDc2NTkwBGdycElkAzE2NTMxODI5BGdycHNwSWQDMTcwNTA4Mzc2NARzZWMDZnRyBHNsawNocGYEc3RpbWUDMTIyNDMzOTMzMg--">
Visit Your Group
</a> |
<a href="http://docs.yahoo.com/info/terms/">
Yahoo! Groups Terms of Use
</a> |
Can email me at [e-mail]
was not sure what to put in for product have Windows xp