So it has been a little over week since I started using Firefox 4 Beta 13pre (64-Bit). This evening I was trying to read an article in Wikipedia but there appeared to be an issue with the character encoding. I switched the encoding from Unicode (UTF-8) to Western (ISO-8859-1) which fixed the issue for a moment but then reverted back to the Unicode encoding (although Western was still selected).
I was going to view the page using IE Tab Plus and got the message “IE Tab Plus can only work on Microsoft Windows.”. Now, looking at the add-ons manager in Firefox I do noticed that IE Tab Plus is not compatible with Firefox 4. I do happened to still have a 32-bit version installed (RC1) so I fired up this build on a clean profile. Loaded the page up in Wikipedia and same thing. However, when I went to install IE Tab Plus, I discovered another version that had been updated this month that does work with Firefox 4. After installing on the 64-bit version, I tried to switch into IE Tab mode and got the message “IE Tab Plus can only work on 32bit Microsoft Windows.” Least that error message makes more sense.
I searched the Firefox Builds forums but didn’t really come across anything that matched my issue. I went ahead and dropped a post on this issue, so we shall see what happens. I do know this is related to Firefox 4 as the page renders fine in Firefox 3.6