I recently sought help over a problem I am having with FF. When I try and load it, I get a message telling me that XUL runner 1.9.2.11 is not compatible with 1.9.2.12. The advice I received was to do a clean install. I have done this a number of times - using the Uninstall option in Control Panel as well as running the uninstall utility in the Firefox program folder. Each time I reinstall, and get the same problem. The only difference is that a few days ago I was installing FF 3.6.10, and that gave the error message that XUL runner 1.9.2.11 was not compatible with 1.9.2.10. I have FF set as my default browser, so when I click on links in e-mails, etc. I get the same failure to load symptoms. However, I found by chance that FF works OK in conjunction with System Mechanic 10 - a maintenance utility I have on my machine. If I select the on-line help option from that Menu, FF loads and runs OK. I can open new tabs and have no problem loading other pages. However, even with FF open, if I click a link in an e-mail, I get the XUL Runner error message. Although not all symptoms are the same, I am also having problems with IE8. When I run the program it loads, shows a 'connecting' message in the tab header, then closes. If I uninstall FF, then System Mechanic selects IE8 as the default browser, and as with FF, loads OK. Chrome and Safari both run OK (thankfully). there must be someone out there who knows what this all points to - is that person you?! Note: Trouble shooting information retrieved using FF when opened with System Mechanic.