FYI -- got this from a list member and thought I'd pass it along
Another change they are making may affect Group Members who seldom post messages and/or rarely access the Groups. Yahoo has begun a purge of inactive accounts in all of the Groups Membership ID's. Some of the large groups that have already been affected by this have lost as many as 300 members.
If you are not an active participant in Yahoo Groups and wish to keep your account active it is suggested that you make some attempt to use your ID to keep them from purging it.