Something has to be different on this computer. The error means "your code is referring to an element in the code that does not exist." Such as:

- A non-existent sheetname
- A sheet number higher than you have, such as might be encountered by looking through each sheet and deleting some sheets along the way. Near the end since there are fewer sheets you get the error message.
- Outside the range of an array

Maybe, paste your code here is easier.