iis 500.19 error on unc path with colon char

i have a web site on local disc and another on unc disk i saw lots of 500 error on logs i wanted to search the problem problem is look like this

when i try to reach on local site http://localhost/http://foo-bar.com

i get a 404 not found error

but

when i try to reach it on unc site i get a 500.19 configuration error like this

    Detailed Error Information:
Module     IIS Web Core
Notification       BeginRequest
Handler    Not yet determined
Error Code     0x800700a1
Config Error       Cannot read configuration file
Config File    \\?\UNC\NAS1\SharedStorage\WebApplications\Default\www\http:\web.config
Requested URL      http://localhost:80/http:/foo-bar.com
Physical Path      \\NAS1\SharedStorage\WebApplications\Default\www\http:\foo-bar.com
Logon Method       Not yet determined
Logon User     Not yet determined

unc site has a full permission with administrative right

iis not started to use any modules before i get this error, so i cant use failed request tracing rule