Upgraded AV from v3 build 684 to v4. XP SP3. Every access of a networked drive throws the following error: Event Type: Error Event Source: EventLog Event Category: None Event ID: 6004 Date: 3/3/2009 Time: 7:31:39 PM User: N/A Computer: OFFICE Description: A driver packet received from the I/O subsystem was invalid. The data is the packet. A few of these are in there as well: Event Type: Warning Event Source: MRxSmb Event Category: None Event ID: 3019 Date: 3/3/2009 Time: 7:26:44 PM User: N/A Computer: OFFICE Description: The redirector failed to determine the connection type. Back to version 3 and all is well again.