the receiver i bought keeps shutting off. when working its great.?

It could be one or a few reasons.  Since you state it works sometimes that indicates its not a wire short, that would cause an immediate shut down or blown fuse.  

If it happens when playing to loud it can either be caused by the amplifier overheating because of poor ventilation OR the amplifier is running out of power and being driven into overload. 

It is important to have proper matching of amplifier power and speakers.  That is a long answer to answer it correctly.  

The most common answer to this issue is your amplifier is running out of power and causing the amplifier to go into thermal shut down.

tt is best to have more amplifier power than you would ever use so your never running the amplifier close to its maximum output which could send a distorted signal to the speakers OR damage the amplifier causing it to go into thermal shut down. 

And lastly is making sure the amplifier can handle the speakers overall impedance.  Many of the cheap receivers on the market are not designed to drive speakers with difficult impedance loads. This is the resistance the speakers present to the amplifier. If the speakers impedance is lower or higher than 8 ohms you need to make sure you have a receiver that can drive lower or higher impedance loads, otherwise you could damage the amplifier or speakers.  

If you are interested in the long answer to picking the right amount and quality of power for your speakers send me a message.

Kevin

as spaceismissing likely has it,a shorted speaker wire somewhere,,impedance mismatch

someone may have ab AV remote tuned to the same frequency your unit is,check the manual for whether it has some programmable  numbers that require setting in the remote keep the volume wayyyyyyyyyy down when in the off position,volume way up when you click on may draw enough amps for a short time to cause system shutdown

Some good advice has been given, but higher-impedance speakers may help if it's overheating. A dedicated fan that helps cool it might not hurt the listening experience too much, either.

There are several possible causes. 

The only one you can easily do anything about on your own  

is making sure that there are NO stray strands of speaker wire 

touching anything other than the correct terminals.     

All other reasons for the problem are technical 

and need to be addressed by an audio repair shop. 

First of all, learn basic English.

Next, without knowing the make and model, whether you bought it new or used, no one here can even guess why it's doing what it's doing.

Check the fuses and how the speakers are wired to it. If none of that works, take it to a good electronics repair company.

Double check for any faulty wiring first. If any wire is damaged or the wrong gauge then it may short the receiver. If it shuts off when a speaker is connected then it's either the speaker wire or the speaker itself with an issue.

If the receiver shuts off when you increase the volume or something then one or more of the speakers might be below the recommended impedance rating and causing a short. For example, the receiver may recommend 8 ohm speakers but there are 4 ohm ones connected. The best bet is to get speakers that are within the receiver's recommended range.

If none of the troubleshooting makes a difference then the receiver itself may be faulty and needs to be serviced.

call or send the manufacturer and let them know it has a glitch and keeps shutting off. demand a refund or a replacement.