Comment 9 for bug 83451

 To repair Xfce panel problem, make sure you have 2 active profiles. The one profile will be used only for main and the other will be your backup. This meaning that if under your main profile you lose your panels you can repair them by, copying .config contents to your main profile hidden files. Please follow this to get your panels back. This problem is profile related.

 Copy the .config directory to another drive preferably neutral like a small fat32 partition or a USB flash drive that has the FAT format. Then rename the .config to config. (rename directory by removing the dot(.) changing this this cause the directory to be seen)

 When the system Xfce crashes, please send crash report via apport. Then open the file manager, Under View, click on show hidden files. Then find the directory called .config. Enter the directory, then look on your neutral partition for the directory called config, enter the directory there and highlight all files and folders, click on copy then return to the current work profile and paste all files and folders in the .config directory. It will ask your if you want to replace all of the current contents, please say "yes", or "yes to all". Once completed, logout, then log back in.
Your panels should reappear.

This is not a permanent fix, but it should get you by or until the developers find a real fix. This works in the Xubuntu 7.10 AMD 64, unsure if it works with 7.04 version.