While rebuilding my Windows system (full reinstall WinXP), my driver CD installed a version of .NET to do its thing. I should have gone to MS and installed the latest version, but did not. I hadn't even got to the point of installing the XP SP3 upgrade at that point. When I installed Firefox and started for the first time it wanted to upgrade an incompatible .NET extension. It hung trying to do the upgrade. Now the only way to run Firefox is in Safe Mode. It crashes immediately on startup in normal mode. I do have several plug-ins installed, but I think they were done by various software packages I installed outside of Firefox...after it started crashing.