i was able to install zimbra and run it succefully on winxp, but i'm facing some problems with my yahoo account.

gmail worked perfectly with zimbra, but when i tried to use my ymail account, which is my main e-mail, zmbra first told me that i'm not using the new calendar so i switched.. it still thinks that i'm using the old classic one.
it also failing to fetch any incoming messages from my inbox, all i managed to do since i added my ymail account is sending messages,
for some reason zimbra agreed with ymail and was sending messages just as it should be doing but always fails to load my messages..

is there anything i can do?
using winxp
Zimbra latest ~ downloaded yesterday.