Keep freezing in the Nether

It could be a host of issues. A lighting texture or animation might not work well with your graphics card and isn't supported, issues with Java? a possible modification or plugin that effects the Nether. Try reducing your video options to render distance Tiny, turn particles off and graphics down to Fast, this will tell you if it is a system resource issue or possibly a compatibility issue.

Get optifine

My computer is brand new... I hate Lenovo.

That is probably lag. It's probably caused by you having a bad computer or laptop. The Nether is more resource intensive, therefore being more laggy than the other dimensions.I suggest when going to the Nether, turn the fog down and the smooth lighting off. Hope this helped.