Windows Defender is supposed to be able of eradicating the
Trojan:Win32/Ceprolad.A,
but maybe the virus has evolved into a new format.
Your only option is to try out other anti-virus products, one after the other,
until the virus is gone. I advice running more than one anti-virus,
even if the virus seems to have been removed, just in case it left something
behind.
If you have a System Restore backup dating to before the infection,
rolling back to it will also help.
The only sure solution is to format the disk and reinstall everything,
but this may be too difficult.
For more information, see the post
How can I remove malicious spyware, malware, adware, viruses, trojans or rootkits from my PC?