One of my Laptops (running Windows XP still) is doing something similar - the WZC service fails to start even though it was set on automatic, and thus none of the wireless connections work until I manually restart it, set it back to automatic, etc. etc. The next time I power up the machine, it seems to be back where it was before -> screwed up again. It worked flawlessly until I let it install the latest XP Service pack from M$oft.
The other laptop, which doesn't have that latest SP, is still working fine.
Both are Dell pcs.
Aggravation. Thy name is Micro$oft.