Row Height - Excel 2010

Help please. Randomly, a row resizes autonomously. When the worksheet is viewed, a single row resizes to some unknown enormous hight so that the entire viewing area is one row high. The information in that row doesn't display however if the the cell is entered into the name box, the cell's info is displayed on the formula bar. If I close the worksheet and reopen it the problem usually resolves. The original spreadsheet was developed under Excel 2001. I recently upgraded to Office 2010 and the problem developed.

I just selected the entire worksheet and reset all rows to a height of 15. I'll see if the problem recurs.