My xp and vista were working perfectly together on 2 separate drives.There were no problems booting. Then my xp (which was installed first) developed some tcp/ip problems after a registry cleaner (stupidly I didn't back up the registry). After numerous failed attempts at tcp/ip fixes the only thing left was to repair the registry. Knowing I could possible lose everything in my xp system, I decided to install a a copy of xp I had backed up a month before I ruined my system. I still wanted to keep the old xp since it had bunch of stuff that wasn't in the backup. Hopefully, in time, I would learn how to fix it or a least get the backup loaded and configured like the first xp. I thought there would be no problem because vista and xp were on separate drives. If things went wrong in xp, I'd always have vista to help recover. After reading a bit of this forum I found out too late how wrong I was. So I decided to install the backup xp on the same disk as the original xp, but it wouldn't boot to the new xp, only to the old xp the first os on the disk. Now at the time I had no idea it was a boot problem, I thought something was wrong with the recovery. The first time the recovery was done to a logical partition, so after reading the directions in the recovery program ,on the next try I did it as a primary partition and then as active partition. Each time I eidited easybcd to boot the new xp, but no luck, only booting to the old xp. Before shutting down I made sure I could boot vista and there was no problem. I could see the second xp was on the drive, so after some sleep I decided the problem was with booting and that's when I started reading the info at this forum on how a boot works. I get home after work and turned on my computer, ready to tackle my boot problem with the help of this forum, only to find out there was to be no booting. Instead I got a "non-system disk or disk error" message. I know all is not lost, but I have no idea about howto correct this problem. I think the mbr has to be replaced, but I don't know where to start. I need step by step help. I am not knowledgeable on boot issues and had no idea I was creating such a huge problem. Please have pity on me and direct me how to get out of this pile of crap I've stepped into.