You've asked a very important question that is related to computers. You've mentioned your problem that your computer restarts when you download something. There are some major factors involved if your computer is showing this problem. In fact one basic factor is overheating conditions. For example there are many types of software like Itune, Media Player and others which do a lot of processing during decompressing and decoding. So due to this , the processor or hard drive can become hot and this problem can occur. You can solve this problem by cleaning the fins on the heat sink that are under the CPU. Also if this problem still occurs then it could be another reason.
There must be shortage of memory. For example , if your computer is trying to access a difficult point in your memory but it can't process it properly, it can cause it to restart the computer. You can solve this problem by removing your RAM sticks and changing their places. So in this case you can get rid of this problem.
If you're using Windows XP then it is pointing towards a system error. So you must make a repair of your operating system. In this way, you can successfully overcome your problem. I hope it is clear now.
There must be shortage of memory. For example , if your computer is trying to access a difficult point in your memory but it can't process it properly, it can cause it to restart the computer. You can solve this problem by removing your RAM sticks and changing their places. So in this case you can get rid of this problem.
If you're using Windows XP then it is pointing towards a system error. So you must make a repair of your operating system. In this way, you can successfully overcome your problem. I hope it is clear now.