This issue can be caused by an extension that isn't working properly.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

Thank you for the advice. Starting in safe mode and then removing addons solved the problem. It appears to be connected to the sync addon. I do not seem to have the complete sync program installed. ie.. I do not have the ""add device "" button, on either machine. However the rest works very well. Regards Martin

You don't need the Firefox Sync extension with Firefox 4+ versions, it is built in.

Thank you. The problem appears to be that both the PC and the Android Xoom think that they are the master and neither offer the ability to add another device. I must have set them up incorrectly. Regards Martin

Locking this post, please post a new question if you need additional help.

-Michelle