Hmmm, I solved this problem recently.
Are you using Fabiano's source ? I may help
EDIT : Well, if you use Fabiano's source you will want to change the port you are using.
If you have that error you probably changed the default port (80) with another because you had troubles using skype or whatever, but you need to use that port 80 !
If that is not the problem, alot of threads are already solved about this error on mpgh