if you are using community server, it coud be memory issue. (cs using to much memory) so, when memory is not avaliable, your app pool will be resstart. its very common thing.

you have two option;

 

1 - increase your memory up to 512 Mb. (if you are using windows vps you need 1 Gig. memory.. thats what I did.)

2 - if you dont have too much traffic in your web site you can change in your communityserver.config file in the /CommunityServer/Core/@cacheFactor attribute from "5" to something like "3" or "2". (this is telligent employee succest)

 

 

have a nice day.