I seem to keep getting disconnected from Steam game servers

[ExAm]

I can only play for a short while on most servers, then I get disconnected for no apparent reason. This happens in every Steam game I play. One or two servers will let me play indefinitely, but the rest disconnect me within the space of ten minutes. What the hell? My ping is fine, and my connection doesn't drop out or anything, so why am I getting disconnected? Are there some ports I have to forward?

[Bastinka]

Peer Guardian 2, Zone Alarm, Firewall?

It doesn't pop up saying anything?
You shouldn't need to port forward as a client of a game.

[CN3089]

What does the disconnect message say?

[ExAm]

"disconnected" :P

[CN3089]

Well, usually the cure-all for connection problems with Steam is deleting clientregistry.blob, steam.dll and steamui.dll from your Steam folder, and Fixwareout (http://downloads.subratam.org/Fixwareout.exe) if you have XP. vhttp://i29.photobucket.com/albums/c251/CN3089/Emoticons/emot-shobon.gifv

[ExAm]

Done. More word on whether that fixed it later.