If have a CD with some file..

i want to scan cdrom evenbefore opening it.

It depends on the type of virus that's on the CD. Basically, there are two types of viruses: executional software virus and document virus.

The first type is the classical type of virus. It only gets activated when you execute binary code that is infected by the virus. If you disable "autorun" on your computer before inserting the CD, and if you do not copy or start any of the programs on the CD, then you are safe from this type of virus. Keep in mind though: if you copy anything from the CD to your computer, you can copy the virus along with the file you want.

The second type of virus is written with the macro language of typical PC programs (e.g. MS Word, Excel, etc.). The virus is basically attached as a macro to a standard document or spreadsheet, and gets activated when you open this document or spreadsheet in Word or Excel.

Here is what I would do:

1) make sure the Anti Virus program on your computer is running and up-to-date (download the latest signatures NOW).

2) scan your computer to make sure there is no existing infection.

3) get as much information as you can about the virus on the CD. It helps if you know what to watch out for. Somehow you know that there is a virus on there, so maybe you can ask someone what type of virus it is?