There are several different snapping options. F8 will enable and disable snapping altogether. However, even with it enabled, nothing will happen with grids or markers until you also individually enable those features (look in the Options menu).

If things still seem messed up, you can reset all of your various preferences to factory defaults (explained below). Understand, however, that if you do this, this will reset all of your various settings in the options and preferences menus. It may take 5-15 minutes to change these back to where they were. However, if your snapping problem is due to accidentally changing some setting or group of settings, this will fix your problem.

To reset all preferences to factory defaults.

1. Press and hold either Shift key on your keyboard.
2. While holding the Shift key, select "Preferences" from the Options menu.
3. Release the Shift key.
4. You will now find a new tab called "Internal." Click on this tab.
5. The first line says "Reset all settings on startup." In the Value column, double-click on the word "FALSE" and change it to "TRUE" (don't type the quotes).
6. Click on OK, then quit and restart Vegas.

One final note: Resist the temptation to diddle the other values in this dialog box.