Unable to bind to port Localhost:8888

Microsoft ISA Firewall client may cause Fiddler Classic to detach. When starting Fiddler Classic under nonadmin account (ordinary User) you may see an error message:

Unable to bind to port [Localhost: 8888]. This is usually due to another running copy of Fiddler Classic.
(An attempt was made to access a socket in a way forbidden by its access permissions)

Fix:

• Close the Fiddler Classic application.
• Open REGEDIT
• Add a new STRING under HKCU\Software\Microsoft\Fiddler2 named ExclusivePort with value False.