Q: trying to install Office on my iMac but the dvd ejects before it install. I know it is not the dvd player as I am able to use it all the time, can someone help me?

If it is a retail copy it's possible the disk is damaged.

also if you mean others as in other computers which were not macs but ran windows then you can't install the windows office on a mac it needs the special OS X version of office that ms makes

Look at the silver side of the disc. Are there scratches, fingerprints, or smudges? FIngerprints and smudges can be cleaned with a lint free cloth. Scratches can sometimes be polished out. See this article for help. You can also contact Microsoft about a replacement disc.