Hi there! It sounds like you're experiencing a frustrating issue with Excel 2010. Here are a few steps you can try to solve the problem:

1. Check your Excel options: Go to File Options Advanced and scroll down to the "Cut, copy, and paste" section. Make sure the "Show Paste Options buttons" and "Show Insert Options buttons" boxes are checked. This will allow you to see more paste options when you right-click.
   
2. Clear your clipboard: Sometimes the clipboard can get bogged down with old data, which can cause issues when pasting. Try clearing your clipboard by going to Home Clipboard Clear All.
   
3. Try using the keyboard shortcuts: Instead of using the right-click menu, try using the keyboard shortcuts to paste as a formula. After copying the formula in B10, select the range B11:B1000 and press Ctrl+Alt+V. This will bring up the Paste Special dialog box, where you can select "Formulas" and click OK.
   
4. Check your formatting: Make sure that the cells you're pasting into are formatted to accept formulas. You can do this by selecting the range and going to Home Number General.

I hope one of these solutions works for you!