Can only join a very few MP server

all other server the VAC bar is one bar away from the end and the download is at 0 but I never can connect. Any suggestions?

AMD 9850 x4
Dual 4870’s
Gigabyte Mobo MA790X-DS4
Mushkin 2x2Gb Ram

Mayby its something with your router?

firewall might see the information comming to your computer as an attack. Just turn it off and it should work