Edit: Case closed! I reinstalled my OS and now it's working.
I've got one Mac Book, one Mac Book Pro and one Mac Mini (the latest version). The Mac Book can easily connect to and browse files and folders using Finder on my Mac Mini via my wifi network but not the Mac Book Pro and I think I've set everything up right - enabling file sharing on the Mac Mini and also screen sharing. Both file sharing and screen sharing works from my Mac Book using the main admin account on my Mac Mini.
When connecting from my Mac Book Pro I'm able to connect through Finder and see the shared folders on my Mac Mini but when double clicking a folder (for example the folder called "Richard") I get this error message:
The operation cannot be completed because the original item for "Richard" cannot be found.
The error message is actually in Swedish, since that's my language, but I'm pretty sure it's translated exactly like this on a default Snow Leopard installation.
Also, a weird thing is that when I first set up my Mac Mini I was actually able to access it and browse files from my Mac Book Pro as well, but just for a week or so and then this error message started showing up. Don't know if I might have changed any settings but I don't think so.
Does anyone have a clue what this problem is due to and how I might be able to solve it? I would love it if I could at least get some hints on how to address the problem - what to look for in the system preferences etc. And please let me know if I'm not giving you enough details!