Comment 48 for bug 439448

Same problem here after the upgrade from Karmic to Lucid. Sometimes I have 2 sound icons where one of the icons should have been nm-applet. Sometimes the area where the nm-applet icon should have been is empty, but the notification area is still sized as if there is an icon and if you aim correctly (there are one or 2 pixels shown) and right-click, you actually get the nm-applet menu.

Removing the notification area and re-adding shows the correct icons again (but this will only last until the next reboot). What also seems to fix this issue is when you place the notification area more to the right. The configuration 'notification area|indicator applet|clock|indicator applet session' shows the behavior described in this bug-report, but when I rearrange it to 'indicator applet|notification area|clock|indicator applet session' the behavior seems correct and I don't experience this issue.

This is a very annoying bug. Not being able to see a crucial icon as nm-applet, with which you control your wireless connections, will not help people to switch to Ubuntu and will not fix Ubuntu bug #1: https://launchpad.net/ubuntu/+bug/1
These kinds of bugs, how small they appear to be to an experienced user, are not helping Ubuntu becoming the Linux for Human Beings that it wants to be.