Invalid Instance Invalid Connection error Connecting to SQL Server using MS Access 2010

When connecting remotely, if an error like this appears:
Invalid Instance.Invalid Connection

with something similar to this in the event viewer:

*+* *System*
*-* *Provider*
[ *Name*] Microsoft Office 14 Alerts
*-* *EventID* 300
[ *Qualifiers*] 0
*Level* 4 *Task* 0 *Keywords* 0x80000000000000 *-* *
TimeCreated*
[ *SystemTime*] 2010-05-26T04:12:37.000Z
*EventRecordID* 18 *Channel* OAlerts *Computer* Matrix2
*Security*
*-* *EventData*
** Microsoft Access ** [DBNETLIB][ConnectionOpen (Invalid
Instance()).]Invalid connection. ** 502687

The following solution has been successful for previous clients:
-Try modifying the Data Source to "IPADDRESS,1433" replacing IPADDRESS with your server's IP address.