lost files after quarantine

Help! My father just put Avast into his windows xp and did the boot scan. during the scan several files were noted as having win32 virus and a couple had win32:hoaxalarm-k. he moved the files to quaratine and now he can not open anything on his desk top and the message the files could not be opened because of wininet.dll is not present. the option given by windows is to reinstall it. he can not even do a system restore at this point. what to do???

okay-- i have my problem possibly solved thanks to an email to the support team. we are going into safe mode and restoring those files. it seems that the virus or worm that got into the system has somehow modified to it to operate. we will then have to back up all personal files and then i am going to take the easy way out and take it to the local computer gurus for medical intervention… clf