I was just building something in Silverlight that makes use of the Isolated Storage, and I uncovered a bug in Silverlight 2 Beta 2 that cause's it to crash and you are unable to write to the Isolated Storage. So, I dug in and found the location on disk where Silverlight stores the files for Isolated Storage.

Here's the file location under Windows Vista where Silverlight stores the files for Isolated Storage:

C:\Users\{username}\AppData\LocalLow\Microsoft\Silverlight\is

Just replace the text "{username}" with the Windows Username of the user the data is stored for.

The bug that I ran into was also causing the Silverlight Configuration dialog (which pops up when you right click on Silverlight content within the browser) to crash when I selected the Application Storage tab. So, this bug prevented me from clearing the cache, and I wasn't able to get my app working again. I just deleted all the files within the above directory and if fixed my problem.

If I figure out what I did to cause the issue, I'll find the place to report the bug.