I'm trying to get my SGS to connect to my home network when my network is in "invisible" mode, but it can't find it -doesn't register at all.
When network is set to "visible" everything is fine.
I have of course registered all necessay data regarding the network manually into the phone -this being gateway, network mask, dns, wep key.
This works fine with my laptops, but not with the SGS.
Any suggestions???

Did you manually enter the wifi network credentials via the "Add Wi-Fi network" option? Did you enter the correct SSID, security type and key etc.?
If so, what is the network type (a,b,g,n)?

well I don't know if this might help you but one of my colleagues had similar issues and he solved it by configuring his wireless router to work on one network type only for example if your router is working on two network types b and g try to set it up to work ONLY on b or g whichever you prefer...

in my opinion I think that network type 'n' is the best type and suits our SGS more than other network types

Like I said earlier, when it's not in invisible mode - everything works fine. Invisible mode or not -all credentials must be entered to access my network.

My router is set to type "G" network only, because I have a few computers standing around and they can't all access type "N".