The virus (as most other similar viruses do today) fakes the address of the sender - so, is your friend really sure that it was you who sent him/her the virus? Anybody else who has your address in Outlook (Address Book, e-mail, or also other kinds of documents on the disk) may got infected and start spreading the virus with your address in the "From" field.
If avast! doesn't find the virus anywhere on your disk, then you are not infected (if you have the latest virus database, of course - currently, it's 0401-9). The file in the Chest is "safe" - it is certainly not spreading.
If the virus is active in memory, the resident protection should catch it - and in this case, it should offer you to "Remove the virus from the system completely" (a new big button in the virus dialog). It would start the integrated avast! Virus Cleaner.