Lost keyboard shortcut for beginning-of-line/end-of-line
I remember having the same problem in some apps after upgrading to Lion. A reboot fixed it for me.

Workaround: use Ctrl+A (instead of ⌘+←) to move the cursor to the beginning of the line and Ctrl+E to move the cursor to the end of the line (instead of ⌘+→). This works in all Cocoa-based applications.