I'm experiencing the same problem as varunshaji.
I have installed Pidgin and after selecting the Office Communicator protocol in the accounts list, pidgin crashes.
Maybe a little late with the reply - but I encountered the same error when trying to set my n900 up today.
I got around it by using pidgin on an ubuntu desktop and copying the settings for the Account entry created into my accounts.xml file on the n900. Now pidgin on n900 doesn't crash and uses the account settings entered.
