I would ensure your running the latest drives for your graphics card.

Run the game in a compatibility layer (windows xp or 7) and potentially also try running the game as an administrator (right click run as) this wont or should not effect the sysdumps but will make the ping time work on the lobby screen.

It could also be caused by your antivirus software doing something funny with ram, so i would also try disabling your av for a game or two and see if this has an impact.

Finally if the systems a few years old i would consider also running a ram test, there is a lot that will cause jo to sysdump even on a stable system, the above are the most likely ones, but i would also download a memtestx86 iso and burn it to cd or usb stick and run a full ram test to ensure its also not bad ram.

My guess would be graphics drivers, joint operations does not like it when you switch back to desktop and then the game, if you have anything that runs an overlay and steals the focus away from joint operations or switch back to desktop whilst in game this is also known to get a sysdump as it does not deal with the focus change so well after xp.

Could also be a a bad file in the game. Try reinstalling the game and if you are running w8 or higher do not make changes in the game file after install as the admin items somehow corrupt the game file. Copy game file and make changes on copy and paste the new game file after install . This typically mainly applies to hosting a server but will probably effect any changes you make to the folder after game is installed.

The game does best with NVidia cards

I got a theory on sys dumps. Although they are a part of the game i never started to get them more until about 2009 when the aussie servers died off and i was forced to start playing on the USA and EU servers. While the aussie servers setting were "how the game was meant to be played" (...the IC Mod battle cry). ie, So, scope zoom ON, FF ON, tracers OFF...for me trying to play on these other "restricted" servers , scope zoom OFF, FF OFF, tracers ON, was not only an alien experience to me...but i also seemed to get more and more sys dumps.

Maybe this is the root issue? When the server has these silly restrictions checked, the game don't like it and is trying to tell you that by causing sys dumps. It's a cry for help. Put me back on hardcore settings..

Anyway...it's just a theory...

It's not possible to fix a .wac file by turning off antivirus, updating drivers and changing graphics settings.