"Invalid Partition Table" - HELP !!!!

Start at the beginning.
Yesterday, my comp would not boot up. Then after a number of tries, I tried a "restore" that comes with my computer when bought. Only this time, it doesnt. For the first time, despite running the whole thing, I get - "Hard Drive Error" so, as my warranty is up, (I did try all the same) I took out the snuffed HD, and moved up my second HD to put my WinXP Home onto. Only it WONT install. I put another smaller HD on to take up the cause, and it asked whether I wanted to partition it, OK I said, only it got through the full 100% (taking 3 hours plus for a 30 gig) and then said it couldn't format as it may be corrupted/damaged (which it isnt as it had been working fine in my sons old comp) So I am baffled as to what to do next. Aha ! I thought. I'll use the western digital "data lifeguard" as they are both WD. It refuses to run the floppy at all. "Invalid Partition Table" is all I get when I try to run the floppy. I change the bios for only floppy boot up and it will not run. Same again - "Invalid Partition Table" so I cant even format the HD's I have left. I have another HD ordered and if it goes the same route I'll be in the same mess. Could anyone shed any light ? :(
(This is being done on my sons computer)

Try a different IDE cable. If that doesn't help it may be a problem with the IDE controller on the motherboard. You could try one of the drives on the other IDE channel that your cdrom drive is probably connected to.

Thanks, SSp. I'll have a crack at that.
I also had a loan of some sort of boot up disk off a friend where it had a kind of Partition prog, and that said 2 parts of the main HD were "active" yet one of them didnt exist ! I split the 80 gig Western Digital HD up into 5 parts, F, G, H, J, K
F was 28gig, and this mystery partition was neither NTS or Fat32, it was "extended" or somesuch (beginning with E anyway !) I couldnt do a damn thing with it. What is it ? It was down as 45 gig !

It gets worse. I took delivery of my new HD and immediately installed it and set it away with the "maxblast" disk utility to partition it. Only now for some weird reason my monitor will not work so I cant see what the hell Im doing. The "on" light is yellow as opposed to the green it should be. I have tried everything. I am baffled.
This has been a nightmare of a month. Everything, and I mean everything has been a horrible horrible experience. My computer acting up and not running at all has been the least of my problems. Getting it sorted would be a slight brake on the disasters though.....:(