multi-level number list corrupted

[MZ]

In a Word 2007 docuemnt, I have dozens of separate (non-continuous)
multi-level numbered lists, that are separated by subheaders. That is, each
subheader level containing its own multi-level numbered list that starts from
1

In the middle of working on a particular list, suddenly ALL these
non-continuous lists became one massive, continuous numbered list, with each
numbered paragraph displaying four number one's separated by decimals, and
ending with a unique number for that paragraph, beginning with 1 and
continuing to the number that designated the last number in the massive
numbered list.
It looked like this

Text Header
1.1.1.1.1
1.1.1.1.2
1.1.1.1.3

Text Header
1.1.1.1.4
1.1.1.1.5

etc.
Text Header
1.1.1.1.1549
1.1.1.1.1550

When I closed and reopened the file, the numbers returned to their original
format.
What may have caused this problem so that I can avoid this in the future?
Thank you

 

[Stefan Blom]

This could be a display issue, only. On the other hand, there is a chance
that the document is starting to corrupt. Try this: Copy the contents,
except for the final paragraph mark, into a new document, and see if that
improves things.

To display paragraph marks (¶), as well as other nonprinting marks, you can
press Ctrl+Shift+8.