How can I make Shift+End select text again?

Shift+End is supposed to select all the text from the current position to the end of the line. For some reason my computer stopped behaving that way yesterday. Now my cursor doesn't move when I click Shift+End.

More Details:

• Nothing happens when Shift+End is clicked
• The End button and other combinations like Ctrl+End work
• Other combinations like Shift+Home and Shift+PgDn work
• Every application is affected
• Alas, a simple reboot did not fix the problem
• I haven't installed any new software recently

Any troubleshooting tips would be greatly appreciated.

I'm using the Sculpt keyboard and I just updated the Microsoft Mouse and Keyboard Center hoping that it would fix the problem. After the update, I noticed (thanks to new on screen notifications) that hitting Shift+End would toggle the Scroll Lock. This caused me to look at my Scroll Lock key and notice that the bottom left corner was stuck down. After fixing the key everything went back to normal.

Interestingly, now that the key is fixed Shift+End no longer toggles the Scroll Lock. It must be some sort of fall-back in case the Scroll Lock key is jammed. I did a quick search but couldn't find any documentation on this.

TLDR: the Scroll Lock key was stuck but I didn't notice it.