Are you in a topic where a member seems to just stop posting or existing? This can happen sometimes. A member may disappear and leave you stuck. Other than posting your character elsewhere, you are stuck.
In this situation, its generally accepted that if a week goes by without hearing from said member, that you can skip them and throw in whatever reasonable means you need to exclude them from the topic. This can be an assumption that their character had to leave because they left the oven on, or other things like that. If they are vital to the topic at hand you might be in trouble.
If you are one of these people that cannot post, please leave a note in the member announcements area that you wont be able to post so that we all know your didn't drop off the map. At least that way everyone knows your not just ignoring them. Otherwise a week without a word means you could be involuntarily ignored/removed in the topic for others sake.