The location detected by avast! seems to be a database file containing info on your contacts: address, telephone number etc. There’s no obvious reason why it should contain malware.

Have a look in the following location and see what you find:

C:\Documents and Settings\christa\Local Settings\Application Data\Microsoft\Windows Live Contacts[snip]@hotmail.com\shadow\members.stg\792002404

If members.stg is not too large (max. 10MB), see what VirusTotal says about it:

http://www.virustotal.com/vt/

EDIT: Removed personal info.