Thank you for your post.
I am unable to replicate the problem. This is what I did.
1. On a Dell machine running Windows 7 Ultimate, I installed FileMaker Pro 10 Advanced.
2. I launched Filemaker Pro 10 Advanced, created a database file (Test.fp7) with a couple of text fields.
3. I entered data for one record.
4. In Layout mode, I added a Web Viewer and set it to "http://www.filemaker.com"
5. I returned to Browse Mode to see the data, and the Web Viewer shows the FileMaker web site.
6. I closed Test.fp7.
I am then able to open the same file again or select another file. FileMaker Pro does not crash.
Let me know what I'm doing differently than you, and I'll try to replicate the problem here.