I uninstalled and reinstalled both CS:S and Source SDK but the error won't go away. What could I do?
Press "reset game configurations" in the source sdk panel.
Hey, it worked xD Will this cause any unwanted side effects?
None. Also, if it happens again, you just need to run Counter Strike: Source and then exit it.
Consider it as a game crash. You reboot and your good to go.
Thanks guys :)