OK, guys, thanks. The problems persist. The HD seems NOT to be jumpered down, I am thinking of the wrong HD, probably the one in my previous 1.7. (This PC is a mishmash of two computers, plus added bits.) I'm quite happy about interfering with the hardware.
My hardware pal also suggested that sometimes RAM works strangely, or only part of it works, so if only, say, 256meg was working, that might explain everything. I wonder if there is a program that tests RAM? It is a single strip, so I can't add to it, because if it isn't up to snuff, then I'll get even more perplexing problems. I've tried mismatched RAM. Never again.
I don't use anything that uses much graphics, but photos and short movies work normally- there is a graphics card in there that sometimes doesn't work properly, showing the 'click' area. I think it's the graphics card.
I'm going to post this now, look at Micks PM, note what's running, and go to Onecare. Back soon.