Tabs Studio installs to a subdirectory in the user’s My Documents directory. By default My Documents directory is on the system disk, but it can be changed to point to another disk or network share:
Network share target in My Documents properties
If My Documents was set to a network share and you run Tabs Studio v1.5.0 installer you get “Tabs Studio requires Visual Studio 2005, Visual Studio 2008 or Visual Studio 2010 installed” error message:
Tabs Studio Setup cannot detect Visual Studio installation
This problem in the installer is fixed in Tabs Studio v1.5.1. Installer v1.5.1 correctly installs Tabs Studio, but when you run Visual Studio you get “Error number: 80131417”:
Tabs Studio add-in failed to load with error 80131417
A .NET dll running from a network share has less permissions than a dll running from a local disk (even with the .NET 3.5 SP1 changes). You need to add a new code group for the Addins directory with FullTrust to the “Code Access Security Policy”. Run the following single line command with admin rights:
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CasPol.exe -m -ag All_Code -url "file://\\server\share\user\Visual Studio 2008\Addins\*" FullTrust -n "VisualStudio2008Addins" -d "Visual Studio 2008 Add-ins"
Now after Visual Studio restart Tabs Studio should run just fine (you may need to re-enable it on startup in Tools – Add-in Manager).
To remove FullTrust from the Addins directory when you don’t need it any more, run the following command with admin rights:
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CasPol.exe -m -rg "VisualStudio2008Addins"
Update: Uninstallation of v1.5.1 doesn’t work if the computer’s System account doesn’t have read access to the Addins directory on network share.
Update 2: If the computer’s System account doesn’t have read access to the Addins directory you can manually delete TabsStuido.dll, TabsStudio.AddIn files and Microsoft.VC90.CRT directory from it. After that uninstallation or newer version installation works fine.
Tabs Studio Blog (organizing Visual Studio document tabs) 
Thanks Sergey! That tip worked perfectly! Now I can use TabsStudio as intended, and I love it! What a great addin and a great idea. Thank you for your hard work, the excellent customer service, and for sharing with the community at large. -Todd Davis
Comment by Todd Davis — August 10, 2009 @ 1:25 pm