It's a common Windower error. There are a few ways around it, but nothing pretty yet. The simplest solution is to not use Windower when logging on there.

Alternatively, if you're not a masochist and if you have access to a second account, you should try booting them up simultaneously. The button will occasionally show up on one of the two. It's pretty random, though, so still not guaranteed. Like I said, there is no decent solution out yet.