Apple wireless keyboard without num keypad

One option is to create ~/Library/KeyBindings/ and save a property list like this as ~/Library/KeyBindings/DefaultKeyBinding.dict:

{
  "\UF729"  = moveToBeginningOfLine:;
  "\UF72B"  = moveToEndOfLine:;
  "$\UF729" = moveToBeginningOfLineAndModifySelection:;
  "$\UF72B" = moveToEndOfLineAndModifySelection:;
}

Quit and reopen applications to apply the changes. Note that DefaultKeyBinding.dict is not supported by some applications like Xcode or Firefox.

In Terminal you can assign home (↖) to control-a and end (↘) to control-e from Preferences > Settings > Keyboard. That will leave you with no key combinations to scroll to the top or bottom of a window though.

It might be easier to just use the default keybindings. In most native text views:

• control-A or option-up goes to the beginning of a paragraph
• control-E or option-up goes to the end of a paragraph
• command-left goes to the beginning of a line
• command-right goes to the end of a line

I can't reproduce this either. However, I suggest that you hold down Command and then press Delete, as an alternative to your method. This will delete everything on the line that's left of the cursor, and will hopefully solve your problem. (You can hold down Option to delete single words. Experiment with holding down the Option or Command key, and pressing either Delete or the arrow keys. If you hold down Shift with either Option or Command and then press the arrow keys, you will be able to select text word by word, or line by line.)