Date: July 23, 2011
After you updated your MacOS to Lion, you may get the following pop-up error message. Many has gotten it.
There was a problem connecting to the server.
URLs with the type "file:" are not supported.
Many has discussed about it. And it seems that some one has found the quick fix.
"Apparently it only comes up when the computer has Time Machine turned on and isn't connected to the Hard Drive of choice."
So, your Time Machine will show up an exclamation mark. So, to fix it, simply turn off the Time Machine if it is not connected to any hard disk.