I have certain items that are no longer being used but I do not want to delete all the information or backup for it.  
 
Is there a way to prevent these items from being entered into sales orders and purchase orders?

It says "Has records in Physical Inventory module".  Is it refering to all the activity that has transacted.  I don't want to lose that.

Thanks works perfectly.

This was one reason why I ended up purging really old sales orders (SM-J-J).
Also, archiving WO's if the item is  manufactured helps.  This might even apply if it is a R type item issued to a work order.  
Also, consolidating inventory transactions might help.  I've done that also.

I went and change the type of item from F to N and then made it obsolete and it accepted it.  Which is weird because some of the other items I made obsolete were left as F.  I don't understand that logic but it stops me from trying to add the item in a sales order which is exactly what I want.  
 
However I still can not make the two that have sales orders attached to them from 1998 obsolete.  I tried the SM-J-J and it says there are no open sales orders in that date range.  When I look at the SO button in the item screen it has a negative quatity on order.  Could that be causing it.