Bad serial number given in setup

[jeijo25 7]

I'm not really sure but when my friend tries to start a game it goes to the screen with the tanks then gives what the topic title says. any ideas of how to fix this?

[Bash Arkin 266]

Launch Combined operations by its self

and then try again.

[Cloud (DayZ) 3]

Step 1:

Exit steam, or to be safe go offline.

Launch Steam as Administrator.

Go to Arma II (the original) and right click and go to Properties.

Click on Local Files tab --> click on Verify Integrity of Game Cache. It will say "1 File failed to validate and will be retrieved"

Now Launch Arma II as a standalone game (ie just launch Arma 2 and not with combined operations).

You can now play Arma II without getting that error.

Step 2:

Repeat Step 1 but for Arma 2: Operation Arrowhead. Repeat it exactly.

Step 3:

Launch Arma 2:Operation Arrowhead with Combined Operations.

It will work.

[jeijo25 7]

thanks :D

to you both