left4dead freezing

Hi, folks. I've been scouring the web over the past few days and have come up with nothing that has helped this issue, nor have I seen any thread about this problem on your site. Several others seem to have the problem but no one yet seems to have a solution...

I have been playing left4dead without a hitch for perhaps a couple months now. Then I ended up getting a trojan that was redirecting me all over the place during searches. I followed some instructions from your forum for a similar infection and relieved the computer of the virus. But now, Left4dead won't work. It loads the Valve screen, the starting cinematic, the lead screen and the selection screen with the lighthouse. When I go into Play Online, I've noticed that a campaign has been picked (before it said "Any Campaign). I change it back to Any Campaign. I select "Find a game in progress". It will find one, load to about 50%, then freeze. I usually have to do a hard shut down as ctrl-alt-delete often won't activate the task manager. I tried today to get on single player mode, and it does the same thing. I have uninstalled and reinstalled this twice but it's not helped. Any suggestions would be appreciated. I want to mention again that this game was working fine before the whole virus mess-up, so I know my system can handle it.
Recently, I've also noticed that standby mode has stopped working. Pressing the keyboard button or going through the start menu results in nothing but about a half second of my cursor becoming an hourglass. Not sure if this is related or not as it's a more recent development.

System: E-machines T5212
Windows XP media center edition, sp3
2gb RAM
Dual core 2.66 ghz, 2.67 ghz
Graphics card: ATI Radeon HD 4650


Thank you in advance.

 

Thank you very much for the quick reply. I will get back to you in a few days (I have a monsterous work week and as such it will take time to go through all the steps).
Take care.
~Brad

 

I had the exact same problem. I some how got this malware on this post
http://forums.majorgeeks.com/showthread.php?t=190826
I played the game for a few weeks it suddenly started freezing and such.
I already knew exactly what to do.. thanks to MG and others.
Just do what Halo says in his post and it should clear it up. Just make sure to NOT SKIP anything. Good luck. :cool

 

I had started doing the scans as per your instructions when I came across the answer. As it turns out, a program called Threatfire is currently not playing well with L4D. Exiting or uninstalling threatfire seems to fix the issue. I was able to play normally. Thanks for your help though... I also managed to clean a couple trojans off my system that I had no prior knowledge of.