extra large bottom row in excel 2010

I've noticed this on only one of my excel spreadsheets. Sometimes, not always, when I open this file, the bottom row on one of the pages takes up the whole monitor viewing area. If there is- for example- 400 lines of data, the next line down won't have a number on the left. If I highlight this overly tall line and delete it, line 401 is now below line 400. I can't seem to be able to duplicate it at will, it just is there when I open this file. Again, sometimes, but not always, maybe once every 5-6 times I open the file. Thanks.
Mark

I'll try that the next time it happens. Thanks.

I noticed it again today. The blank line fills up the whole monitor screen. I can see the top of the blank line, but when I scroll down the next line with datathis blank line is not shown. This blank line has no number assigned to it on the far left column. I never do see the bottom of the blank line. If I delete the blank line, the remaining lines with data move up. There are sometimmes more than one of these overly tall blank lines. I'll try to do a screen shot of what it looks like and see if I can post it here.

I tried what you suggested and so far all is well. Thanks for the help.

Mark

I noticed it again today. I've posted a screen shot. line 2630 is the last line that has data. The next numbered line is 2632. I added the 9,8,7,.... to see which line gets blank and it was line 2631. If I highlight the large blank line and delete it, the number 1 I put there is no longer there.

Sorry for the long delay in replying. Method 1 is too confusing for me. I did Method 2 and it still, at times, shows the extra large last row.