Can I stop payment on a rent check?  I just moved in?

Stop payment on that check and you could be charged with Bank Fraud...

You arent getting out of that lease. 

I will say, laundry 4 times a week for one person is pretty extreme.  My family of 4 gets away with 3 loads a week...  I'm not saying the roommate is right to complain, just wondering why you need to run 4 loads (with the corresponding electricity costs) a week. 

First time with roommates?  Consider it a learning experience.  Actually, what you describe isn't so bad, compared to many other stories I've heard.  I'd tough it out for the next two months, then decide what to do.  It's only two months.  One possibility is to find out why your roommate is complaining.  Maybe he wants to use the machine, but finds it always busy.  Or maybe the noise is disturbing him.  That kind of thing can be fixed by adjusting your laundry schedule slightly, then everybody wins.

If you stop payment on that first month, you are committing criminal fraud. You have lived there one month. If you don't pay for the 2nd and 3rd months, you are in breach of your lease.

Since you signed, a 3-month lease, you MUST stay the entire 3-months.  When a house owner cashes a check - is their business.....not yours!

You signed a lease, a contract.  Read your contract.  You break your lease you will have trouble in the future getting an apartment. This will haunt you. 

Learn to ignore him. Agree with him.  Yes I do a lot of laundry each week.  

If you stop payment on the check, the landlord can sue you for 3x the amount. Your argument is with your roommate and not the landlord. I work 7 days a week with different clothes each day and only do 2 loads a week. If your roommate is concerned about the water and electric bills, offer to pay more towards them. You can't "forget" about a lease. Your landlord would have the right to sue you for the rest of the rent for the period of the lease. Contact the landlord and ask why your check hasn't been cashed.

You can't sign a lease, then stiff the payment for rent. That's illegal and stupid. And you'll be at fault no matter WHY you did it. Stick out the 3 month period and then look for either another roommate or another place to live. Don't put yourself in jeopardy over such a dumb issue as how much laundry you do. And ignore the issue as much as possible. Someone else has no right to tell you how much or how often you should be washing your clothing. 

You're going to end up in front of a judge and have to pay the rent and penalties. You're discussing STEALING from the landlord. You need to discuss with them where the check is and why it's not cashed, and replace the check if needed. Where do you get off even asking this question? The other roommate isn't in charge of how often you do laundry. Moving out because you're too chicken to tell him to STFU is not a valid move out reason.

If it hasn't been cashed then you can stop payment on it. The landlord can take you to small claims court for rent owed.

If the check hasn't been cashed, the bank will let you stop payment, for a fee, But that doesn't get you off the hook for the rent. You signed a lease. If you don't pay the full amount, the landlord can and probably will sue you for the rest of the rent money, and will win.