This is something I’ve known about for awhile, but was reminded of how much I love it after having to deal with the irritating confirmation pop-ups and the little “ding” sound effects that Autocad loves so much when we upgraded to 2008. If you issue the command EXPERT and set it to 2, some of those confirmations will go away, while not affecting things you need confirmation for. Here’s a list of what your options are with this command:

0 - Issues all prompts normally (default setting)
1 - Suppresses “About to regen, proceed” and “Really want to turn the current layer off?”
2 - Suppresses the preceding prompts and “Block already defined. Redefine it”, “A drawing with this name already exists. Overwrite it?”, and “x object changed to a frozen or off layer and removed from the selection set”.
3 - Suppresses the preceding prompts and those issued by the LINETYPE command if you try to load a linetype that’s already loaded or create a new linetype in a file that already defines that linetype.
4 - Suppresses the preceding prompts and those issued by UCS Save and VPORTS Save if the name you supply already exists.
5 - Suppresses the prompt, “That name is already in Use, redefine it?” issued by the DIMSTYLE Save option when you supply the name of an existing dimensions style, as well as everything above.

When a prompt is suppressed by EXPERT, the operation in question is performed as though you entered YES at the prompt. Setting EXPERT can affect scripts, menu macros, AutoLISP, and the command functions. Therefore, it is recommended that you only set the level that will provide relief from the most annoying pop-ups. My personal setting is “2″.