Having this issue? Well I have spent alot of time trying to find out the cause of this issue. I have also tested it on multiple Operating systems. The issue in part is contained to only vista and xp. I will first describe the issue and then tell you why it happens. Then I shall show you a fix.

THE PROBLEM
When you launch steam server browser or the in game browser and you allow the refresh to build a list for a decent period of time you will notice your server list get in to the couple thousands of servers to show. Once you find one you want to join you click to join and a small window appears that shows you the players in the server and the ping, which at the time shows normal. When you click the join button again you will notice the ping jump to about 2,000 or more in ping showing a timeout and you can no longer join the server. You will also notice after quickly exiting that your internet browser has timed out and any other internet based applications that you try to open will also time out as if your connection had "locked up".


THE CAUSE
This is due in part to two circumstances. One which is evident in most windows machines that are running 32-bit. The cause is do to the limitations imposed on windows machines after the SP2 service pack for XP and vista alone. This limitation is a TCP/IP limitation that only allows you to have a max of 10 half-ope connections at a time. This is usually due to any application such as steam that opens several thousand connections to all the servers you refresh. This easily overloads this limit it also creates an event in event viewer of your MMC. The event is known as: EventID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts. Microsoft implemented this to prevent worms and malicous attacks from happening from a single connection. While it is a good idea it prevents applications like steam server browser from operating correctly and unfortunately when you can only have 10 half-open connections at one time it queue's the rest of the connections up until they build to a point in which your connection "locks up". This limit is imposed on XP and windows vista. It is however not the same for every version some may not have the limit. or the tcpip.sys file may have already been over written.

THE FIX
There is a fix but there is also a catch. This does not work on 64bit versions of XP that are post SP2. It works on all 32 bit versions of vista and XP.
if you have windows XP 32bit use the following link: http://www.lvllord.de/download.php?url=en/EvID4226Patch223d-en.zip
Download that file unzip it and run the evid4226patch22.3d.exe file it will edit your tcpip.sys file for you after it completes successfully simply restart your machine and try verify the problem has been removed.

For vista users please see: http://www.mydigitallife.info/2008/02/17/download-vista-tcpipsys-and-uac-auto-patcher-to-increase-tcp-connection-limit/
Read the instructions carefully and insure that you fully understand them before attempting to use them.

Please note that this does not work on all 32-bit systems sometimes your tcpip.sys file alreayd has no limit and sometimes the patcher can't detect the tcpip.sys file. Basically it may not work for everyone.

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