Download the Tool Attached to this FAQ or you can download it from Intuit
http://support.quickbooks.intuit.com/support/networking/nettool.aspx
Then install it and run the QB Connection Diagnostic Tool
Click on The Scan folder tab.
Add the folder where your quickbooks files are located then
Press Scan Now.
You will notice that it will correct some Permissions Status's now you should be all good to use quickbooks on remote computer again.
If that does not work you will need to manually Enable the Firewall
Go to Star, Control Panel, Services, Stop QBCFMonitorService and all QuickbooksDBxx Services then Rename the Files below and start back the services after you are done.
Incoming Ports
tcp
80,8019,56722,53343
Outgoing Ports
tcp
80,8019,56722,53343
Then inside your quickbooks folder
Rename .ND file to old
Rename .tlg file to old