Transferring files over wireless network

Hey everyone,

So I'm about ready to throw my desktop and laptop out the window. Simple problem: I have a wireless network setup between 2 computers with a homegroup, but cannot transfer files between the 2 machines. It used to work, but suddenly, all I get is a message saying I need permission to perform this action.

I've gone into the advanced sharing options to make sure everything is configured properly (on both machines). Network discovery on, password protected sharing off, etc. I've made sure to share all the folders I want to work with manually through the right-click "share with" menu.

It just won't frakking work.

I can SEE the files I want to work with. For example, I can access the data drive in my desktop (from my laptop) and play a music file. But I cannot transfer a file from my laptop to my desktop.

Both machines are running Windows 7 Home Premium. Lappy is 32-bit, desktop is 64. Both machines are connected wirelessly.

I'm normally really good at solving my own problems with Google searches. I've looked around and found several threads detailing similar problems, but I've tried all the suggestions - still no dice. If anyone has any ideas, please share. Otherwise, I'm gonna have to resort to beating my wife.