IIS entries Disappear

[iis-newb]

I have this problem on one of my servers where random site entries in IIS seem to disappear without provocation.

These sites will still resolve to the server however they only load the plesk default page.

Has anyone else had this problem, and has anyone seen a viable solution to this problem ?

 

[Pavluha]

If you use Plesk you should create domains in Plesk only.
Please check that this domains is created in Plesk.