Typically, this question comes up with regards to IPCOP preventing users from accessing a server. There are many factors which can cause this to occur.
- Make sure you are not running a local software firewall (and disable the Windows Firewall).
- Check if you can access the server from within the zone (i.e. a computer on Green can access a server on Green).
- Make sure all appropriate rules have been added.
- If the server is on Orange, check the Orange Mantra.
- Attempt a ping. If this fails, check for a software firewall.