Still having problems? I changed some settings in my router and got the dreaded "Access Denied" popup. Since that was the only thing I did, I knew it had to be related to that.
I changed the router settings to the way they were originally but still got the "Access Denied". I reset the router using the "reset" function in the router's setup page and still got the error. I powered down both PCs and powered back up and still got the error.
Then I powered down both PCs, powered the router off for about 5 seconds and powered the router back up. Then powered both PCs back up. Guess what, the "Access Denied" popup did not happen and I can access either PC from the other as it was before.
Try powering everything down and powering back up. Even if you did this before, things you changed after that can apparently affect stuff.
Long shot but maybe worth a try,