Problem with applying skins in WB 5

I posted this in Object Desktop before I realised I should have done it in WB. Apologies for the double posting.

I've just installed WB 5, and it seems that everytime I apply a skin, nothing happens. However, after restarting my laptop, the skin seems to have been applied to the desktop. Applying Windows Classic or WindowsXP is fine without rebooting.

Thanks in advance to any help.