I have Social security disability benefits, and my teacher disability benefits direct deposited into my checking account. Sometimes I deposit other checks in there too. Can my bank account be frozen?

You need to make your bank aware of it because they can freeze it and then you have the hassle of fighting to get it unfrozen. Some exceptions can include federal government, taxes, student loans, child support,

Commercial creditors cannot garnish your Social Security retirement check. However, the Federal government may garnish your benefits to recover student loans, back taxes, or any other monies owed to the Federal government. Additionally, your Social Security retirement check may be garnished for current or back child support.
Can creditors garnish my Social Security retirement check ? (http://www.ssdrc.com/retirementquestions22.html)

If you have mixed funds in the account, often they can freeze it, till they sort out what money is what.