Archive
How to get an instance of Microsoft.CommerceServer.Runtime.CommerceContext.Current
As a quick recap, once you created your Web Site from Visual Studio using the project template (see those links: http://msdn.microsoft.com/en-us/library/aa545520(CS.70).aspx and http://blog.duc.as/2009/12/30/commerce-server-2009-r2-and-visual-studio-2010/)
Next step is to configure in the web.config the Commerce Server Membership Provider (http://msdn.microsoft.com/en-us/library/ms917174(CS.70).aspx)
And the last thing is to make sure you have set correctly IIS configuration, specially if you are using IIS 7 since it works different than previous versions you could face an execption like this:
“Event handlers can only be bound to HttpApplication events during IHttpModule initialization”
If so, check you not using an Application Pool running in Integrated Mode. It should be Classic. (why not another link 
http://n2cms.codeplex.com/Thread/View.aspx?ThreadId=38311)
All this are my finding in order to get an instance of CommerceContext and the UpmMembershipProvider.
Hope some of this helps.
Adrian
Error installing Reactive Extensions: Please wait while the installer finishes determining your disk space requirements
Today I was trying to install Reactive Extensions for .NET (Rx) on my Virtual Machine and got this error:
Please wait while the installer finishes determining you disk space requirements.
Searching a bit I found solutions for similar situations with MSI installers, the workaround is using command line and msiexec (http://bloggingabout.net/blogs/harold/archive/2009/01/14/windows-installer-doesn-t-finish-determining-disk-space-requirements.aspx).
Since in this case it is a .exe my solution was to run it from Windows PowerShell and it worked.
Here is a sample:
powershell C:\Users\Administrator\Desktop\Rx_Net35_SP1.exe
Hope this helps.