Serious problem after Avast Scan

Hello, I’m having a problem with my Windows XP machine.
Avast detected some infected files and I decided to do the antivirus scan. The infected files appeared to be in the system folder so Avast restarted my computer scanned the entire hard drive before Windows completely booted. It detected the infected files and prompted me if I wanted to move them to the Avast Chest or delete them, I chose to move them to the Chest. After the scan was finished it resumed the Windows boot process but after it was almost done it asked me for my password to log in, after I did so it logged into Windows only to log off immediately after and taking me back to the password dialog box. I tried putting my password severaltimes and restarting the computer but it keeps doing the same thing, it logs in and logs off immediately, I cannot access anything. I’m guessing one or more of the files I moved to the Chest was some essencial system file and now everything is lost.
Is there any way to recover the files I moved to the Avast Chest?? How can this be done now that I cannot log into Windows??
Will I have to reinstall Windows all together?

Thank you very much in advance for your help

Try booting in safe mode,by tapping the f 8 key while booting.
I have a friend who recently had the same problem ( unresolved unfortunately )
Did you need a password to log in ,before Avast removed the virus ? My friend did not,so in his case the virus created the password problem.
If you can boot in safe mode post back.

You could also try a rescue cd

http://www.free-av.com/en/products/12/avira_antivir_rescue_system.html

http://forum.avira.com/wbb/index.php?page=Thread&postID=730130#post730130

http://www.freedrweb.com/livecd/

Overinstallation can solve the problem and you won’t lose your programs, settings, data, files, etc.
Just choose ‘Repair’ installation of Windows and install ‘over’ the old installation.

http://support.microsoft.com/default.aspx?scid=kb;EN-US;315341
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q314058
http://support.microsoft.com/?scid=kb%3Ben-us%3B315341&x=15&y=0
http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/doug92.mspx

Unfortunately not, we already ask for a feature like that… but for one reason or another, they’re not being able to implement it.