If you are getting the dreaded “Received fragment out of order” error message while playing a Steam game (Counter Strike, Team Fortress 2,etc..) try one of the following fixes:
Since this problem is basically saying that your computer has received a packet out of order it has to do with your internet connection.
1. Run the following steam network diagnostic steam://support/?Issues=*&Tests=Ports
Make sure all steam can access all ports, if the test shows ports which it’s not able to access then that’s causing the error message (look at #3)
2. If you are behind a router make sure you have the latest firmware installed
3. Disable any firewall software that you have running and see if the problem continues
Zone Alarm has a bad habbit of causing this problem for some people
Tip: 95% of the time it’s either your firewall or router that’s causing this error message