Sometimes it helps to enter the /sync command. (I created a macro for that and a couple of others.)
A couple of times when the 'mapserve' pop-up comes on screen, I hit the sync command and a couple of others, and go back to the game. (Doesn't work every time, but I'd say 90%) I used to use them all the time on my old computer and they still work.
/macro GFX reloadgfx (this dynamically reloads the graphics...your screen will go wonky for a few seconds, but it is is supposed to. Don't be alarmed)
/macro SYNC sync
/neterrorcorrection 1 (For better connection to server)
or
/neterrorcorrection 2
I really hope these work for others as well as they have for me when needed.