If your Combat Arm closes within 1-5 minutes, without any hacks,mods, or tampered files, and you're on windows 7, you may be in the same case as me. I'm on Windows 7 64bit and I myself crash without any unnecessary programs running along with it, within 1-5 minutes. I've read a official thread on the Nexon site stating that there is indeed a specific problem with Windows 7 users both 64 & 32bit users, and also may affect Windows Vista users, causing these users's game to crash. Apparently this is due to something with the registry that Windows 7 has, which I for one do not understand, due to myself playing countless hours on the exact same computer that I am bounded to now. Another thing to consider is that it was posted in 2011, and you'd think that it would be resolved by now. I've recently submitted a ticket to Nexon, five days ago and it is currently still in the "Open" stage and hasn't been assigned to any staff member. I've been on the hunt for a "fix", you would say, to attempt to rearrange my registry files, or any files really, that would be somewhat of help to lengthen my gameplay, but sadly, I haven't found anything that stood out. I've updated all of my windows files, via Windows Update, but there are no signs of hope. Sure there are some remorseful thoughts in my head that I even thought of re-installing this game, but I shall stay persistent and hopeful.
I hope you stay the same as well, if there are any updates or even small tips that are useful, I'll be sure to notify you.