Microsoft provided the basics for drivers and you still encounter folk that do this upgrade and stop.
They forget that the drivers are not updated by Microsoft or Windows Update. They often need a reminder to go back to the machine's maker for the rest of the drivers for EVERYTHING.
HOWEVER SINCE THIS IS JUST THE BROWSERS I WONDER. Skype and it's plugin interferes with copy paste so it could be a factor here. Have you considered uninstalling any app that has plugins?
I have a Dell XPS M1530 laptop which came with Windows Vista. A few weeks ago I upgraded it to Windows 7 and ever since then, the numbers aren't working when I use any kind of internet browser. They work just fine while using any other program, but when I use Internet Explorer, Firefox or Google Chrome they show up as the last key that I typed. This goes for when I press shift to type symbols as well. Whenever I want to type a number or symbol in an Internet browser I have to copy and paste it from notepad or a word document. Really annoying.
Anyone have any solutions or trouble shooting tips other than starting over? Oh and I have upgraded it to Windows before on a different hard drive but when the old hard drive crashed, I had to use Vista because I lost the disc for 7.