Question: We're having to reboot frequently (once per day) because we're getting a 9001 error from SQL Server on our VPS.
Rebooting seems to resolve the problem, and we're discussing it with our provider.

Q: Does everyone lose their session scope when we reboot?

Answer: 
Yes, assuming that you are using ColdFusion's session scope in memory. All memory is cleared when the server is rebooted. Sessions could persist if you are using a database or some other external source.

And for what its worth, the application scope and server scope are also cleared.
Miguel-F's answer is correct but here it is right out of the Horse's mouth ([Adobe docs](http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec0c35c-7ffb.html)). I googled "coldfusion session server restart" to find it -- 3rd result. The second result was the originally asked Stack Overflow question from 2010. 

> 
> **Session**: Contains variables that are available for a single client browser for a single browser session in an application.
> 
> 
> Useful for client-specific information, such as shopping cart
>  contents, that you want to persist while the client is visiting your
>  application.
> 
> 
> **Data is stored in memory and times out after a period of inactivity or
>  when the server shuts down.**
> 
> 
> ColdFusion Administrator lets you select between two kinds of session
>  management, Standard ColdFusion Session management and J2EE session
>  management. For information about types of session management, see
>  ColdFusion and J2EE session management.
> 
> 
> Use the Session scope prefix in the variable name.
> 
> 
>