Your directory is broken somewhere. You don't know where, we don't know where. The directory is like the old fashioned card catalog which tells your computer where all the files are located. Your card catalog is bad. If you are lucky maybe only those files are lost which a system installation (same old one or upgrade) would replace. Alternatively, it could make things worse and would be like your mother going in and cleaning your room for you. We can't tell you because we don't know.
Buying a brand new computer would only help if you don't plan on transferring your files from the old one. If you do, you may suddenly find you get a file error message. Or worse, you don't get a message but 2 years down the road when you're trying to open some critical document you find it is corrupt. Frankly if you are considering buying a new computer as a fix for this, why not just erase your whole hard drive (and lose all your files) and still use the old one? Wiping the drive is like burning down the library and building a new one. At least you know there won't be any corrupt catalog if there aren't any books to list. 🙂
The bottom line is, if you like playing it safe the only thing to do is repair the drive (and hope it can be repaired -- some directory things are beyond any tool).
