. Try starting up in Safe Mode. This prevents a lot of drivers/services/&c from loading. If it will boot, run a Registry repair app (I use RegSeeker, but there are many, possibly better, others available). If it still won’t boot normally, start removing/reinstalling apps and drivers (if you don’t need them, don’t reinstall). You may want to run RegSeeker after deleting apps, to remove any garbage left behind.
. You can make Windows display what it’s loading during the boot process (but I don’t remember how to do it off the top of my head) and maybe pinpoint what is causing the problem. Unfortunately, just because things go awry when X is loading, that doesn’t mean that Y, which loaded earlier, isn’t the culprit.
. If nothing seems to work, try booting from a floppy. If you can’t boot from floppy, you probably have a hardware problem. If you’re brave enough, open it up and check all the connectors. Loose connectors are common in laptops, since they run hotter (which exacerbates creep caused by temperature cycling) and get bumped around more. Unfortunately, repairing an older laptop will probably be impossible (lack of parts) or more expensive than a brand new one.
. If none of that works, backup any files you want to save and reformat. Either boot into Safe Mode or boot from a floppy to copy your files.
. If there’s nothing on the drive you want to save, it would be a good idea to just go ahead and reformat it to get rid of any errors that have crept in over the years the drive was in use. I reformat my drives every 12-18 months (or sooner, if I suspect a problem). If the drive is more than 3-4 years old, it would probably be a good idea to do a low-level format, too.
. Hope that helps. Just remember, I’m a Newbie, so verify all this before you start monkeying around. If you’re not mechanically inclined, don’t open the case - you may never get it back together.