I have the exact same issue. I've verified game files multiple times, made sure my system is good w/ no background programs, etc. It's bogus. I didn't have this issue in the closed alpha test, but it's been an issue since the game was in beta in the fall. Bogus.
I've seen it mentioned a lot in-game, but haven't been able to find a thread on here or on steam related to the game just hanging at 100% after finishing a game on any server. Once a map has been selected and the countdown ends, the map load screen begins. Once the loading reaches 100%, game audio begins, but I'm stuck on load screen. I have to alt+F4/alt+tab out and completely relaunch the program. This has happened in EVERY instance of map change.
Ridiculous. Any fix? Having to relaunch the game is not acceptable.