it could be the configuration file. go to the config folder and delete the game.conf and try again.

first i start by getting the sword, then i just go and kill zombies until i have enough points for the box, i grab the ak47 and begin fireing at 0 0, using this stratogy i got to round 33

Here is the way I solo missions. It's pretty much Connor's method but with a few modifications
start by getting the sword
then kill zombies till you can open the door at 50 50 and the door at 76 50
Kill zombies till you have 1500 points, which should be during round 4, and pick up the juggernog at 83 100. This increases your hp to 100
Using this method you can totally ignore the box, which costs way too many points, since you have plenty of hp to take a few hits.
Head to coordinate y 0 and go to x 150 or 200, killing zombies as you do. After round 5 the sword will take two hits to kill the zombies, which is fine, as you can just hit them, move away from them, and turn and hit them again.
Wait for a fire sale and fill your two weapons with cz 75 and ak 47
Use the cz 75 during rounds about 6 to 8 as it's quieter and only takes two hits to kill the zombies. You should not need to use fire sale anymore after this, since you'll probably get enough max ammo drops that you never run out of ammo.
After round 9, use the ak47, as it's a bit stronger, and can generally kill the zombies in 1 fewer hit than the cz75. So if it takes 3 hits for the cz75, it will take 2 for the ak47.
If you ever get insta kill, switch back to the cz75, move left, and be extremely aggressive to make the most of insta kill time. This is super important because insta kill time lets you finish rounds quickly, so you can get to the harder ones sooner. Be really care about zombies that spawn in front of you if you're moving left, because you don't have much range in the front if you're facing that way. But don't be afraid to spray bullets because max ammo drops happen pretty often.
Pretty easy, it just  becomes a matter of being patient enough to regenerate your health if you get hit, and using insta kill mode to your advantage. Though there have been a few times where insta kill mode didn't actually let me insta kill the zombies which was sad.

Insta kill seems to glitch a bit. I don't know when or why that happens.

@tony78:
Thanks tons. That fixed it. Any idea why that happens?

Thank you!  One thing still eludes me: when I hear someone dying how do I get on his name?

Ok thankyou!

U s server is down i believe, i can't reach it, but i can reach other servers

To be honest i think they are implementing the update so it probably will release soon.