There are several bootable CDs you can download and try.
with detailed instructions here:
If you understand the registry then the offline registry editor is useful:
PC Regedit. See the instructions in the BOTTOM half of
Most of these infections will mess with userinit (should be c:\windows\system32\userinit.exe, ) or shell (Should be explorer.exe) in
Usually the following registry entries are involved:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings "WarnonBadCertRecving" = "0"
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings "WarnOnPostRedirect" = "0"
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon "Shell" = "%UserProfile%\Application Data\antispy.exe"
tho you sound like you may be seeing several infections at the same time so you may have more. IF the PC won't boot after running a scan it's probably because the malware was removed but the registry entry was not so you will have to go in with PC Regedit and fix it.