[Edit: this is now redundant, as a corrected version has been released]
Restoring the errored seconds data is straightforward (up to a point), if a little tedious. Because the file es.data is only saved on program exit, the most recent copy you have will be from the last time you shut down DSLstats. If it's more than a day old then it's probably not worth fully restoring - just use the procedure below and remember that the data for earlier than today will be shown against the wrong day.
1. Work on the saved copy of es.data (we'll assume it's saved as es.data.bak).
2. Load es.data.bak into a text editor.
3. You'll see that the file starts with a pair of large numbers which you can ignore (they're not currently used) followed by a lot of similar sections headed "Days ago = nn", followed by 24 pairs of numbers representing the up and down data for each hour of the day.
4. You need to insert one (or more) of these 25-line sections immediately after the initial pair of large numbers, to push the other data back to where it belongs. Insert the following:
Days ago = 0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
0,0
5. Now you need to edit the "Days ago = " lines so that the numbers run in sequence from 0 for the first one to 100 for the last. Delete any sections at the end which would exceed 100. Save es.data.bak
6. Shut down DSLstats.
7. If you want, you could now copy the "Days ago = 0" section of the newly saved es.data file to the same position in es.data.bak (overwrite that section, don't insert it). Save es.data.bak again.
8. Delete es.data. Rename es.data.bak as es.data
9. Restart DSLstats.