help please

Ok thanks for all your help. I talked to Dell and they had to send me a new XP disk, and recovered my xp with reinstalling the boot.ini file and hall.dll file, which I have no idea how it was corrupted. I did nothing else except use this software and restart my computer. I am troubled to say the least because all my programs microsoft word excel, all need to be reinstalled, and lucky me cant find the disk. Also I need to use remote desktop and its gone from my accessories file. all my programs are gone from the porgrams tab under the start tab. I obviously dont know what or hwothis all happened and I dont even know what the registry cleaner does. I merged the registry tab and had hoped it would fix the above problems however that does not seem to be the case. My question: Is there any way to have my computer go back the way it was before I used this CCleaner and registry cleaner. I have mcafee virus running could this mess things up.?? Thank you

I installed and used this program Windows XP: I used the CCcleaner basic cleaning and the Registry Cleaner selected all without thinking. I did click make a back up. However and I used the regedit software download and merged the back up. Nothing really happened. Im not sure what was supposed to, but had hoped the following would have been fixed. . My computer is completely dead now. At first all my programs dissapeared from the all programs tab and I could not run word, excel, itunes, anything except internet explorer, then I restarted and I now have the following message. Windows cannont start because the following file is missing or corrupt Windows root system\32\hall.dll reinstall copy of above file I must say I have never come accross a program that completely took out my computer. I am very worried as all my music and life pictures are on this computer. Please help if you can. Thanks, If you dont know can you please give me advice on where I might find help. Thanks again.