Counter Strike: Source Connection Failed

I recently received a new computer for Christmas and it runs a lot better than my old one. First thing I did was download CS:S and ARMA II, two games that I couldn't play on my old computer. At first Counter-Strike was running fine, but after I downloaded ARMA it began to have little connection hiccups which have screwed me over more than once. Then those hiccups became more frequent until eventually I could only stay in a room for about 2 minutes (1 round) before it would give me the WARNING: Connection Problem text. Then it seemingly fixes itself, only everyone on the map is invisible to me but they can still kill me. I try leaving and rejoining, and that fixes the invisibility problem, but the cycle just happens all over again. My ping is usually around 44 and I have a 5.71 Mbps down/ .42 up connection. I also have an Xbox 360 and a PS3, which I also play regularly and rarely get connection problems on those consoles. this is extremely frustrating to deal with and I'm trying to get into competitive pc gaming. I highly doubt that it's my connection, because the internet works fine on everything else, even ARMA II.