Hard drives record information as magnetic 1's and 0's. With time, these charges get weaker, unless they're periodically rewritten. Any read-write activity is enough. Problems can happen when certain bits are only read, such as the Master Boot Program. There are any number of utilities that will periodically "fix" read-only sections to make the disk work. Personally, I've used Norton Utilities the most. Run from a floppy, any such utility suite will make your older drives boot. Best regards, Jim Griffin Wed, 8 Jul 1998 01:09:34 +0000; Mark and Judith Walter wrote: > I have some older hard > drives(in the 202-328MB range)have tried them on a number of > different machines and get "Invalid System Disk, Replace the disk and > press any key."when starting up. If I put a bootable floppy in, it > will boot up and I can look at C: and all seems fine. -- Prometheus was the first Beta Tester. Sisyphus was the Corinthian Systems Administrator.