Black screen loading screen

Happens when you join a game then when the game loads (like 1/4 of the bar full) it goes to a black screen and you have to wait a LONG time (for me its like 7-10 mins) Windows XP, was fine since I basically started playing like 1 month when the game first came out. Never had this problem until I came back like 3 days after the zombie patch... Cmon saiden, hurry up I'm getting ****ed on joining/making games only to find out the game has ended/last round... or when I play ZM and im the host and by the time i finally load up we're at like wave 14+. I cant even finish missions without the game ending when I actually load hurry!!