I have "windows xp" and I am having trouble removing this file: "virusisolator.exe" from my computer. When I try to delete, it will say "access is denied." How can I remove it?

Check out this link, I think it will be of help to you.

VirusIsolator.exe - Program Information

Options depending on why access is denied:

You don't have file system permissions:
Login using administrator account and delete file.

File is in use:
a) Kill the process using the task manager if it is running (most likely since file is malware), or
b) If you're running antivirus with real time scan and viewing the file in Windows explorer, wait and try again, or
c) If file is shared, see who has a lock via Start > Control Panel > Administrative Tools > Computer Management > Shared Folders > Open Files. Have person close file and delete it.

All that said, I occasionally encounter the same problem in XP with files and I have to: Hit F8 while booting up, choose safe mode, and delete the file.

Or in rare occasions: Install the recovery console from the original operating system CD and load into that and delete it from the command line.

There is also a Microsoft utility called Process Explorer you can use to invalidate (with risk) any Explorer file handle while running Windows.