There are many ways to Automagically save your workbook. And, the advice you recieved about Excel self corupting cannot be overstated. Make a copy now. Put it in a safe place.
Now on to Passwords. EXCEL Password protection is a Joke!.. It is easily bypassed. I use it here just to remind the users that they are in an area that they should not be typing in. I do not expect it to protect anything.
I also use the PW OFF PW On routine at the beginning and end of some routines that change data in protected cells.
Lastly, you may want to create an on close routine that checks today's date compares it to a string you saved with the date of the last back up you made and if X days have passed create a Copy in a folder of your choosing. That way if something terrible happens you can delete your corrupted file and use the latest back up. You can also set this up to save two, three or a zillion files and over write them when certain conditions are met.
Lets say you want a copy each week. But, you want to protect yourself if the file corruption occurs during your last SaveCopyAs routine. You could have a file saved as Copy1 And another saved as Copy2. your routine would check, before it saves, to see if copy one or two was the last saved and save the file as the other one. This way you would increase your chances of having a file that would work should the worst happen and you end up saving a corrupted file. And if all else failed, remember that backup you made, now would be a good time to get it out.
Yours in EXCELent Frustration
KniteMare
While this on close event is a bit complex you can do it by placing your changing values on a hidden sheet and referenceing them with your code. If or Select Case statement s would be used to evaluate the conditions and tell the routine to procedd to branch A, B C, etc.